Source: my well connected Democrat lawyer sister
Clooney was speaking for his good friend Obama. Obama wants Biden to withdraw. So does most of the Dem party.
Biden cannot be forced out with the 25th Amendment because then the Republican-led House of Representatives would get to veto any new VP. IOW, VP must be agreed by both houses of Congress. There would be an impasse which would likely be decided by the Supreme Court. A Rep would become Kamala's VP.
The only move the Dems have is to pressure Biden to voluntarily leave, which Jill and Hunter have no intention of doing. Clooney was part of that pressure. The pressure campaign is intensifying and will continue to do so.
It is already too late to get any other names on the ballot in several states, including swing states the Dems must win. They can't afford to forfeit any states. That's why they can't just parachute in Clooney, Michelle O., etc. They hope he will drop out voluntarily before the convention when they could legally replace him with someone other than Kamala.
Since the debate the Dems have been insisting Biden go out repeatedly hoping that he will shit his pants or fall off the stage. He's come close, but is doing just enough to stay in the race. If Biden withdraws then Kamala becomes President immediately. The only problem is that Kamala is widely, and rightly IMO, regarded as a witless moron. Google her "yellow school bus" speech if you don't believe me. Hell, Google any speech of hers. She got her start in politics on her knees (Google Willie Brown) and became Senator from California because she did the will of her Big Tech donors without fail. Those donors, who give billions to the Dems, also got her into the VP slot by threatening not to give unless she was chosen. The party do not believe Kamala can win and do not believe the propaganda polls that say she has a chance. Internal Dem polling shows that she does not.
There's an open civil war going on within the Dem party right now because they have no good options.