Agree with the hold comment. Perry did have an arm while riding, but his hold was getting pretty high (up to Evans' throat). To me that's crossing the line between a tough ride and being dirty.
I'm not in the business of questioning a man as credentialed as Tom Brands, but I couldn't help but think that Evans should have cut Perry right away in the 2nd round of OT, to maximize the time he needed to score a takedown. Odds were he wasn't going to ride out Perry (and he didn't) and by trying to ride him out first, he didn't leave himself much time to score after Perry escaped. Evans was getting in on his shots so I thought cutting him and having 30 seconds to score a takedown seemed like the best strategy.