No. People have weird beliefs about what fiduciary duty means. It does not mean that companies are required at all intervals to maximize revenue or profit.

Dunno - is protecting yourself from high-profile criticism by doing whatever you want with assets you 100% own and are under no contractual obligation to share ... also in fiduciary duty?

It is not illegal to be petty during business negotiations.

Why? Even if the common myth that public company executives must maximize profits at all costs were true, it's easy to construct a plausible explanation for why one might believe in good faith that destroying 538 rather than selling it is the best strategy to maximize profits. For example, because they think the profit they'd lose from 538 competing with their own politics offerings outweighs the amount Silver would pay for it.

the easy argument otherwise would be that if they sold the IP, they wouldnt be able to revive it in the future, and also they would have nate silver as a competitor in the space

Nope. There is really no case law to support such a legal theory.