The problem is they are also most often adopted by highly informal organizations. In this environment CoCs are most often tools to for the project leaders to carry out personal vendettas rather than equal enforcement of the code.

Sure, CoCs aren't panaceas (nothing is when humans organize), they're just tools to help increase transparency and get alignment. Much like a nation's constitution is useless if the de facto ruling structure doesn't actually listen to the rules in its own constitution; we shouldn't abandon codified rule of law because some polities refuse to respect their own codified rules.

In this particular case I agree, a CoC would be too-little-too-late. But if there had been a CoC it would be easy grounds for dismissing Felleisen (assuming the allegations are true) with little (but still some, since power abusers die hard) fanfare. Now there will be a whole bunch of witch hunt politics and the community will suffer the more for it.