He's currently behind the mango Mussolini in the polls and, other than "at least I'm not the other guy" being a much less effective strategy for an incumbent than a challenger no matter how awful the challenger is, this is the main reason.
Biden may be a corrupt right wing reactionary, but he's not enough of a fool that he's not beginning to realize the fact that he probably has to change course on this or run a very high risk of losing the last fair and open US presidential election.
See, you're an example of someone older who SHOULD be working since you actually WANT to rather than HAVE to. More power to you and I hope you get to keep working for exactly as long as YOU want to!
Cases like yours isn't what's driving the increase though. A combination of economic desperation and pro-corporate gaslighting is forcing and/or coercing people who would prefer to retire to keep working many more years. THAT'S the majority situation.