When you turn over items/money to an FC bank, you're in effect willingly giving it to anyone that is able to take from that bank.

Them exercising their rights and permissions that was given to them by the FC is totally allowable. GM's cannot possibly make a 'moral' judgement in cases like these, they're way too subjective. That's why there's concrete rules, and don't allow for interpretation when it's possible to do so.