I'm not saying its generally good. I'm saying the bad guys are killing each other, hooray!
I'd much rather it happened to it without warning, just an RPG to its helicopter or some hero with a knife out of an alley, I feel like the effect of that would be better, but this isn't a bad thing.
it takes seconds, other way takes years, and its not worth risking it getting away. it's not human anymore, and its a danger to humans, so if its not down for trying to be human again; kill it. don't waste the effort when there are living people who need help.