I think the answer is because we trust Brainy when it comes science.

[ Cos thinks she's raising a valid point and wants to help with any doubts. ]

But since you asked, resisting a telepath is like trying not to hear someone talk. You have to make so much mental noise that finding anything useful is hard. It's obvious when someone's singing the same song in their head or picturing a steel wall to count the rivets. I have nothing to hide here.