If you Dremel cut around the rim and remove the base of the case the bit should come out with it right? Then you would be able to collapse the case inward to loosen it .
Yes, if he was able to cut away the entire web. I can't tell by looking at the pic if he has enough exposed though.
I wouldn't be optimistic he could "turn " it out with a good set of vice grips, but if he had access to a robust single stage, maybe locking on with vice grips and giving a few sharp blows to the vice grips them self might get it moving ?