I understand why he did it, but let it go another 5 seconds Herb!
With the UFC's history with various politicians, most notably John McCain, who want to have the sport banned, the last thing the UFC needs is for someone to get seriously hurt or worse, especially now with the sport on the rise.
I'll pretty sure that the refs are told to stop a fight if they have any doubts.
That said, I still think the stoppage was a good one. Ken wasn't defending with either his arms or, more importantly, his legs. If you watch the fight again, you'll notice that Ken's legs were spread wide open. That's not an mma guard. That's a guy getting f*cked mma style.
Ken put on a nice show once the fight was over, but I think if you gave him some truth serum, he'd tell you he was glad it was stopped.