Re: What do I do if someone anchors too close?
If it bent the stanchions AND the stanchion bases enough to lift them from the deck (the only way the sealant under them would move) then it probably also partly tore the mounting bolts through the underside of the deck. That's now a question of structural damage and water incursion to come, so the $200 or so to replace anbd recaulk two stanchions right now may be only a fraction of the damage.
And then next time when you DO lose your outboard and the damage is a fast thousand dollars out of pocket...remember, you let him walk away this time, and that's just going to encourage him and reinforce his view that YOU caused all this damage.
Dude needs an attitude adjustment, and there are folks like the insurers who will do that for you if you pick up the phone and fill out a paper.