I had this exact issue. Dremel, hacksaw, and drill finally freed the kickstand from the bike, but then the ruined bolt had to be removed. I did eventually get it off with locking pliers and a lot of force. I like the freezing idea, but never thought of that. I just kept trying different ways to keep the kickstand in place (I had no bench-mounted vice) and longer-armed pliers to get more torque. Eventually it came free. Then I replaced the destroyed top plate with a newer version that is cupped to hold the chainstays a little more securely.