It's not the cooking, it's leaving them tightly wrapped in the foil (anaerobic) and not refrigerated; and then not reheating them hot enough to destroy the toxin. The toxin is destroyed at less than 100C, but not the bug.
I usually wash them off, poke them, lather in butter, wrap in foil then cook on the grill. Never been sick
The issue seems to be with storing them after cooking and before consumption.