Luckily I didn't get scammed by this guy, but I'm quite sure he is a scammer.
1. When I asked him about showing me the account in game to prove it was his, he kept saying "hold on....hold on..."
2. After he finally "came back," he said he had to restart his computer. Funny thing is, he never signed off AIM.
3. I asked him if recovery questions were set and he said no. I went to the recover lost account page on Runescape and checked, and recovery questions were set.
4. He joined Realpoor today, which means he's probably a big time scammer like rune-wow on another account