After hearing the entire explanation from Midwak, Gary was unsure whether he should be happy or not. There were a number of reasons to be frightened by this whole thing. The punishment for breaking a vow seemed quite high.
On both ends, it wouldn't do them any favours. The reason why Gary had survived in the Underworld and had gotten this far was due to his Werewolf form, so if that was suddenly to be taken away, then what would he do?
Old enemies such as Ben Clove would be able to take him down, and new ones as well that would always be trying to uproot his position. Then again, the other option didn't sound delightful either.
Essentially, it was no different from a Crazed Altered. When one was unable to turn back and he was sure that the blood lust wouldn't be good either.