Harris:

"If the public health professionals, if Dr. Fauci, if the doctors tell us that we should take it, I’ll be the first in line to take it. Absolutely. But if Donald Trump tells us that we should take it, I’m not taking it."

Kamala says she would not take a vaccine recommended by Trump, even if recommended by scientists. There is no way in the US for a vaccine to be publicly available without FDA approval so the only interpretation that makes sense is one where even if the FDA approved it, if Trump also approved it she would not take it.

Biden:

"Look at what’s happened. Enormous pressure put on the CDC not to put out the detailed guidelines. The enormous pressure being put on the FDA to say they’re going, that the following protocol will in fact reduce, it will have a giant impact on COVID. All these things turn out not to be true, and when a president continues to mislead and lie, when we finally do, God willing, get a vaccine, who’s going to take the shot? Who’s going to take the shot? You going to be the first one to say, ‘Put me — sign me up, they now say it’s OK’? I’m not being facetious."

Biden says he does not trust the CDC and FDA (at the time) because of political influence.

This is not what she said. She specifically said that if public health professionals and Dr. Fauci recommended it, she would take it. The "if Donald Trump tells us" has an implied 'solely' and that is not hard to figure out given context, where in the same statement she says she'd take it if the public health professionals recommended it.

> Biden says he does not trust the CDC and FDA (at the time) because of political influence.

Not what he said. He was asking for more transparency, and suggesting that that needs to happen for public opinion to sway in the direction of getting the vaccines; in particular, during the Trump administration when the public was repeatedly fed lies about all sorts of things.

Both are more nuanced than you are suggesting, imho.

With the history that Trump had for firing people who did follow unreasonable orders (e.g. Rod Rosenstein), it becomes entirely plausible that he would fire any FDA head who did not support a vaccine, regardless of the science behind them. As things turned out, the studies did support the vaccine, but it was not unreasonable to draw a distinction between unbiased experts and experts under threat of firing.