That is an interesting thought process

Being that I was thinking of it as an immunity more than an active ability
It's basically "on" all the time. Kind of like a genetic thing more than an active ability.

In my mind his thoughts would be "blank" to telepathy and he "feels" any intrusion to his mind. Kinda like feeling a bug crawl on you.

Which I could've phrased a bit better in his character sheet >.>
I didn't think that one through for phrasing >.<

Edit: 
Maybe I should phrase that better in my cs