I think we have to be careful about slinging accusations around over this. To be clear, I don't think this is of the order of the Jamie Mitchell/Fulton Bookiegate incident of 10 years ago. If Ryan was doing anything underhand, I don't think he'd have been so willing to pose for photographs and talk to Jonathan Sutherland. I think it's pretty clear that unless something changes drastically, Stevenson will be playing as a sub at best until his contract at Firhill ends. It also strikes me that Stevo has quite a substantial ego, and he'll be unwilling to play that part.
Unfortunately, Stevenson is one of those players that Thistle fans (myself included) were at best lukewarm to, and this season he's done himself no favours at all. There may be a perfectly plausible scouting reason for Stevo to be at Rugby Park, but all the signs point to a player who's run out of time at Firhill.