question about can not kill a bluename

today i saw a bluename outside of minecave but no matter what i do, i can't hit him and he is laughing at me.
anyone know how is that possible?

you can't kill ppl in TC map nowadays. He prolly killed sum1 in minecave and ran out. Weird that minecave guards didn't get him tho'.

U can only attack guards and monster on TC map