Mercenary mode crashing client - opting out doesn't work

I turned off merc mode because it crashed my game after every bg. It worked for a few bgs but now it's putting me in opposite faction bgs again, I check my settings and merc mode is still turned off (opt-in checkbox is not ticked). Help?

I'm assuming this is cause I'm not playing on the warmane client which is impossible for me since I'm on a mac from 2011 and WOTLK is the only game I can play on this old computer that can't run wine or other setups for warmane client / other WOTLK servers with custom content. I see the post about 'modernizing arena teams' and I get worried it will make it impossible for warmane players who are on mac to continue playing, at least arenas.

Anyway now I'm stuck with merc mode so my game crashes after every bg ends. What to do?