I haven't dropped threading due to not knowing someone's canon, but due to not understanding a post. At all. There were a couple of times that I just didn't understand a goddamn thing that the person was trying to get across and felt too bad to try and ask them to change the post to make it understandable to my weak little puny human brain.

I try and thread with anyone, regardless of canon. I don't know crap about most of the big-ticket canons here, and try not to let that get me down. If someone particularly shiny shows up, however? TAGGED WITH NO REMORSE.