Because under the 25th Amendment, the only members of the cabinet who get to make that decision have to be confirmed by the Senate. And as we know, Trump has gotten around a lot of oversight by appointing acting secretaries. So don’t miss this!
.@SpeakerPelosi: “Tomorrow, by the way, tomorrow, come here tomorrow. We’re going to be talking about the 25th Amendment.”
— CSPAN (@cspan) October 8, 2020
Full video here: https://t.co/5q4HIglmaZ pic.twitter.com/8Jeim87yJM
"Pelosi, Raskin to Hold Press Conference on Introduction of Legislation to Establish a Commission on Presidential Capacity." pic.twitter.com/WrgH8Giucq
— NotATweeter16 (@NotATweeter16) October 8, 2020

This whole deal is baffling.
What the hell can a Commission of Presidential Capacity do legally?
The Constitution can be amended by a 2/3 vote of the Congress followed by 2/3 of the states approving the amendment; or a Constitutional Convention can be called.
You can’t change the language of an existing amendment.
It can be repealed and then rewritten and passed again.
Pelosi behavior and demeanor, especially of late, has come into question.
How she’s helping the ’cause’ is debatable.