I think that pretty much nails it. This is Zuckerberg's life - social media & nearby segments - and he's still in his prime (very active, attentive to threats / paranoid) as a competitor in the business sphere. If you give him an opening to cripple Twitter opportunistically, he's going to take a shot.
Did Musk think Twitter actually had a moat (thus he didn't have to be overly concerned with his actions promptly sinking the ship)? It would be hilariously delusional if so.