People in Israel keep referring to him as "a right winger" and talking about the him before he got shot.
It seems this was always him. It's like if a Muslim terrorist commits jihad and murders a peace now activist because they are Jewish. Their racial hatred supercedes common sense or alliances. So too regarding temple mount. Their absolute mania about Jews ascending the mount means they would kill a peacenik hippy arab loving guy like Glick because he ascends.
I haven't seen evidence that he wasn't always like this. When he first got shot I read that when he went on the Mount he would try to sing with arabs or some such