I think the flip side is that Nick Clegg is probably not a great choice of person to threaten. He's already had the utterly miserable experience of going from unusually popular politician to person personally blamed for reneging on commitments in the coalition government (a route he chose for himself), he's not American and doesn't live there any more or particularly want to go back, and is politically connected enough to not struggle to put together a legal team that's happy to take on Meta, potentially without him even needing to dip into his fairly deep pockets.

And frankly getting into a shit fight with an unpopular American billionaire where he's actually the good guy would be pretty good reputation laundering for Clegg, and make a book Brits would be inclined to dismiss as self-serving nonsense sound like it had actual revelations in it. And he'd probably greatly enjoy doing a round of podcasts and TV interviews where he's not the bad guy saying sorry any more.