It's entirely possible that he wasn't being insulting. The comments about stupidity are largely RJ's, and his amazement that people just didn't get it.

I was a little surprised but what you missed myself - then again, remember that even occasional posters spend time on the encyclopaedia-wot looking up info on characters and chapters, etc. Back on wotmania, I thought someone was being totally asinine and dismissive of my post. Turns out it was just the lack of emoticons.

My guess is that Slayer is very dedicated to his evil activities and would tough it out in Emond's Field for as long as he could. He would've felt safe because he can choose (presumably only when he goes from TaR to the real world or vice versa) whether his face and body are Luc or Isam. Also, Perrin was the only guy in the whole Two Rivers who was antagonistic or suspicious of him. That's a lot of buffer for an arrogant guy. Remember, he has Lan's and Rand's bloodlines in him, and he's EVIL; that's a lot of arrogance for anyone...