As in, he couldn't have known so much if he wasn't one of them? I don't think he would've been killed by the police if he was a Freemason. He was cleared because he was in the DeMolay society as a child, his superiors may have been lax about it when they learnt that. But that doesn't mean he continued down that path. Lots of people turn against the religion they are born into when they become adults. Or develop strong moral feelings.

I'm looking for some kind of admission, such as him signalling that he's a Freemason unambiguously, that's what might convince me.