And what would happen if they did not comply?

It's sort of like the mafia 'suggesting' you make a donation. Or a politician 'suggesting' a donation for expedited service. Which is legal.

https://www.youtube.com/watch?v=zgUvwcU6P7I

That's a stretch. They could have decided twitter was non compliant and started treating them a little less gently but would they order content be removed or issue fines or some other direct punishment? Probably not.

This is a failure of imagination.

https://thefederalist.com/2019/09/27/schumer-intelligence-ag...

Yeah, this article is really very imaginative.

If you look at the revelations from Zuckerberg‘s letter this week, you will see that they were not good faith recommendations. They were highly aggressive demands made in forceful ways. Remember, the administration that issued these demands is also in control of the agencies that regulate the same company. For example, the FTC, who could determine that the company is acting anti-competitively or whatever else. They are in a position of power above this company, and therefore, even if they had made the suggestion in a friendly way, it would still be from a position of power that could compel them.

Good faith meaning they believed the analysis of likely disinformation was correct and not politically motivated.