I think EXO-ls had mostly worried he'd been involved since he's friends with Seungri. I think the 5 revealed so far are all the people that were in the groupchat (from what I heard)I wouldn't count out SM yet. EXO's Sehun's name is afloat in the rumors of who was in the chat.
If he did know about it or was involved i'm going to be ranting and raving for months.