Yes, it applies in this case -- although its usually 48 hours.
First note: The White House lied straight up about the speech being delivered "live"; it was clearly not. How do we know this with absolute certainty? Biden had a watch on and it is visible in some of the shot -- and was not at the time of the speech. You'd think the production crew would have enough marbles rolling around to catch this but... nope. It thus was quite-clearly taped and therefore the obvious question is "how many takes were done and was it continuous?" One lie means the rest is presumed a lie.
Others have commented on the obvious use of a teleprompter; I don't care about that as there are few people who speak extemporaneously in such a setting (I might be one of them) so I don't find that troublesome in any way -- and incidentally the teleprompter is visible as a reflection in the "window" but again, I don't care and frankly neither should you.
The real question isn't so much about the optics (e.g. a "sound stage" for the speech as opposed to where it is supposed to actually be in the White House, etc.) as it is the substance.
The party of "democracy", so the Democrats claim (while smearing the GOP as having no respect for those principles) just committed an act of deposing someone they determined had outlived his usefulness despite the will of the people and coronated his successor. I remind you that Harris received exactly zero votes for President in the Democrat primaries this time around and in fact polled around 1% in the 2020 election season, forcing her out of contention before anything really going. Now she's presumptively on the top of the ticket despite having not received a single vote in a single primary and no, being someone's VP is not the same thing as the head of the ticket -- and we all know that.
Indeed it is exceedingly rare that a VP selection has any bearing on the outcome of a Presidential race.
The real question is how it is that President Biden went from "I'm in the race and I'm going to serve the next term" to "its time to pass the torch and by the way I'm unilaterally choosing who it gets passed to" in the space of less than 24 hours. What Joe Biden (at the urging of his party, of course) just did may well be the most undemocratic means of selecting a Presidential Candidate in the history of the United States. Literally no President in history has hand-picked his successor on the ticket unless I've missed something in our nearly 250-year history -- but I don't think so. Indeed the closest analog I can find -- which did have an actual primary season and such -- was Humphrey, who lost (along with Wallace, a third party candidate) in 1968 to Nixon.
What happened is not "illegal" in that as I've repeatedly noted over the years you're not owed a choice at all on a Presidential party ticket -- that's the nature of the game for this office. However, it remains true that to claim you're the "Party of Democracy" when your succession system looks an awful lot like Khrushchev being deposed out of the USSR in October of 1964 is far beyond the realm of "bad joke" and into the realm of actual communist control, at least within the party itself. Indeed the parallels are striking in that the Khrushchev event was a true "palace coup" at that time orchestrated by Leonid Brezhnev with the cooperation of the party -- and of Brezhnev who succeeded him.
We just saw that identical dynamic play out in the Biden White House.
Not even European parliamentary systems play the political game this way in the modern era; if its "time" for someone to go they call snap elections to settle the question with and by consent of the people.
It is of course up to the American people as to whether they accept this sort of Soviet-era style "coronation"; I certainly will not vote for any ticket that is constructed this way under any set of circumstances. In America we are supposed to select our leadership via fair and open elections and those who put together a ticket by other means should, in a Representative Republic, be repudiated at the ballot box and lose. Indeed there certainly is both foreign and domestic improper influence in our elections and has been for quite some time, particularly when it comes to funding, and despite FEC regulations those rules are wildly flaunted and nobody is ever arrested at the time (and rarely prosecuted after the fact), even though detecting such games is quite-trivial in the modern era of computer databases and thus detecting that someone who is on a fixed income, has no real assets and lives in a modest home -- or is even in a nursing home -- has "somehow" managed to donate hundreds of thousands of dollars to political campaigns is known within days or weeks.
But there is a profound difference in character between candidates vying for a nomination and ultimately the general election while funding for the various political jousts, including outright smear campaigns, is less-than proper and some group within a political party, after the primaries are complete, deciding that the people's choice for the ticket must be replaced and orchestrating that without again having that choice of successor made by voters.
The "claim" is that Democrats generally have overwhelmingly ratified Biden's action via donations, endorsements and accolades. Whether that's true or not its immaterial in that in America we're supposed to select candidates who have a primary structure for their office at the ballot box and a person's candidacy does not confer the right to assign a "win" in said primary to another person no matter who that other person might be -- and I remind you that money is not supposed to vote; that authority is properly delegated to the people.
I've argued that for quite some time we're a post-Constitutional society and that the Republic, in fact, is nearly extinct. Certainly in the economic realm we have become divorced at the federal level from the basic requirement to fund government programs with current taxation in that deficit spending is at its core assessing those not yet old enough to vote and in fact those not yet even conceived, say much less born, for the spending voters and politicians wish to do today. That is a profoundly undemocratic act and that future generation or generations has no obligation to quietly consent to that down the road. Indeed such an undemocratic levy has, historically-speaking, been a major factor in the collapse of nations over the course of human history.
But this is much more "in your face" and begs the question as to whether the premise of America, as established by the Founders as a Republic and at great personal cost, still exists in meaningful form within the political sphere at all.
Americans will decide in November and that decision is likely to have extraordinarily profound implications not only in the political sphere but in the economy and asset markets as well.