If he had no previous history of this shit, then fine, slap on the wrist. But this guy has something wrong with him, and it's more than just "adrenaline."
The point of submissions in MMA is to put someone in a compromising position until they surrender, given a reasonable amount of time.. This isn't NHB fighting, FFS, Pearce tapped pretty damn quick and it seemed like this guy just wanted to inflict damage.