Just returned from Cozumel, and I saw the same percentage of "touchers/nontouchers" as I have viewed in the past...about 1 out of ten. However, the "one" was a doozy. He made a point of pointing out interesting things to me (I was carrying a video camera)---right before he "interacted" with the subject. Before I could stop him, he literally goaded and pushed a feeding turtle until it relocated. (He informed me that he was disappointed that I backed off when he did this. He was about to "give a good show" by RIDING the turtle.) I was positioning to get a good view of a nurse shark resting on its belly under a ledge when the shark unexpectedly moved. I'd move too if that same guy were tugging on MY tail! He chased a flounder although I was trying to get a shot of how perfectly its markings blended in with the rock it was on. The list goes on and on. Did I express my displeasure with him? Yes, but possibly not adequately. Did I report his behavior to the DM. Didn't have to--the DM saw it for himself and spoke with the guy.
However, the others on the boat (we were a mix and match boat--my group and at least a couple of others) were extremely cautious of handling the marine life. We took photos, studied intently, and then went our way. It's the same rules sane people should observe where ever they are in the wild. Don't pester the bears, give the buffalo a wide berth, and let the hiding fawn keep hiding (its survival may depend upon it). Don't hack the vegetation and step lightly in delicate growth. What makes us think it should be any different underwater?