Check out the Megyn Kelly interview of Tapper and Thompson. They talk about the 1st two, not much about the 3rd, but the implication is that Jill played a large role. Or download a copy of the book (and send a copy to me).
What makes you think that that cabinet would have invoked the 25th knowing the truth? The Dem's position was that anyone was better than Trump. According to Tapper, Biden didn't meet with his Cabinet, but the Cabinet members had to meet with the 4 people in his inner circle, and they allegedly passed that information along to Biden. However, that's not an excuse for Cabinet members not to fulfill their duties to citizens.
There is no way to spin this other than as a blatant coverup by the administration with the complicity of the media (either knowingly or failure to do their job because of bias).