Regardless what your GM said or not - claiming a staggered mob isn't stealing cause you don't have the ability to let it be claimed (and there are jobs that can hold several mobs claimed)
So in my eyes - if someone "steals" your/my staggered mob - it's your/my fault and you/I don't have to complain about it.

And for those people who didn't understood my previous posting ;p has a clear meaning - google it if you don't know!