Welcome to the forum sdupond...
As long as that shot is fatal, I think the cottommouth is then pretty well harmless. If you stuck your finger on a fang messing with a dead snake, it may be an issue, but I doubt the fish are gonna go messing with a dead snake. Although, if a big catfish tried to swallow the dead snake whole, it'd be interesting. I suspect the upper and lower jaws would keep the fangs inside the mouth and protect them from sticking the catfish's stomach or throat...
