We only saw him incapacitate people so far, and that was to save his own life. I'd be more inclined to believe he's good, considering his final comment about keeping his promise to Skye (I know that could also be seen as a threat too)
They wouldn't flip flop with him twice imo. Some of his basement scenes were filmed to make him look truthful. He's not innocent but he'll rejoin the team or at the very least redeem himself in death, especially after Coulson's decoy comments. And don't forget, we actually saw the flashback of the well!!
On the topic of May's fightscenes, am I the only one who gets snapped out of the illusion when a 50 year old woman mean-mugs and puts her dukes up only for the camera angle to change instantly to show a 20 something gymnast doing all the ass kicking?? They might as well put a fake moustache on the stunt "double".
In other news, completely changed my opinion on Bobbi Morse ("has a knack for picking things up quickly") Morse and Hunter. I was on the fence with both characters but Hunter is a great comedic voice for the show and ol jedi baps is way hotter than i gave her credit for.