They could get the account back quite easily so it's worth very little as collateral. Theymos may not choose to restore the account if he knows in advance but he probably wouldn't get involved with the dispute.
I disagree with you Hilariousandco This post shows accounts can be used for Collateral and some accounts are worth quite a bit. I'm not sure what Badbear or theymos position on this is but, PG seems to have informed badbear of the transaction.
My point still stands. I never said they
couldn't be used as collateral, but that they are essentially worthless as such because they don't guarantee anything. You still have to trust that the person isn't going to easily reclaim them which they can do at any time.