If they tried to get her to step aside and she resisted, it would have looked bad for the party to try to sideline a female POC.
Dems painted themselves into a corner by picking Harris for VP in 2020. At Biden’s advanced age they should have seen the high likelihood of him only being able to serve one term, which would leave the VP in a prime position to be the nominee in 2024. In 2020 she was humiliated on the debate stage and didn’t even make it to the first primary. Yet they chose her anyway, and Biden foolishly committed to choosing a “woman of colour” as VP leaving her as the only logical choice.
This series of poor choices for VP goes back to 2008 with Obama choosing Biden in the first place. He had to have known he was a potential successor and it set into motion everything that led to Harris eventually being the 2024 nominee.
American politics are full of poor VP choices - for BOTH parties. Agnew, Shriver, Mondale, Quayle, Gore, Kemp, Lieberman, Cheney, Edwards, Palin, Biden, Ryan, Kaine, Pence, Harris, and Walz - who might be the most head-scratching choice right next to Palin.
The inevitable upcoming book on the campaign complete with insider leaks of info are going to be harsh on the Walz pick and Kamala’s poor judgment leading up to it.