It seems like a fault that wouldn't hurt the entire system, but it may cause a dilemma similar to Facebooks design flaw, where disowned groups could be taken under control - http://mashable.com/2009/11/10/facebook-groups-hacked/. As with every such flaw, it's likely to start attracking spammers, and should be dealt with in some way (Facebook seems to have disabled reclaiming ownership of groups without admins?)