Aside from the issue of tumah, it’s pashut that going to the Har Habayis provokes terror. Yes, they already hate us – if you were alone in an alley with someone stronger than you who hated you, would you spit in his face?
Those who go up to Har Habayis have blood on their hands.
The Beis Din of the Eida Decries Jewish Violence in Response to Terror