Stupid or cowardly?

Just zealots and talking heads.

He won't listen anyway.

This is what your fellow 'Mericans put him there to do, so just cross your fingers that Chiner is mainly rolling their eyes at his bluster.

Then stupid and cowardly are two likely possibilities.

At the same time, if they're like most people in the US (and elsewhere for that matter), as long as they have relatively well-paying jobs, they're going to stay put. They know that having work in the Trump WH is not a resume builder in the reality-based universe, and quitting now (whether or not they become whistleblowers) is no different from quitting or being tossed on inauguration day 2021; the damage to their character and career has been done. And they have rent to pay and families to feed. And a GS-13 salary or its equivalent is much better than nothing.

At the same time, remember that many of these people are True Believers. They may very well see Trump as their savior and that his reign will last at least through 2024, if not beyond, so some of them may think they're pretty secure for a while, even as we in the reality-based universe see them as something a tad lower than pond scum.