Why is everyone so concerned with Choy, and asking him to "prove" his Faith?
Has anyone asked you to prove yours?
Besides, why are "known" Orthodox so concerned about what he says about Roman Catholicism? Seriously, folks....relax a bit. If he claimed to be Orthodox and was preaching anti-Orthodox dogma in the Faith Issues Forum, then you can question his Orthodox knowledge, but, as that's not the case, I suggest everyone back down a bit.
I've had a number of jobs in my life. I've been trained thoroughly for each one. As it is, "jobs" don't last forever anymore, and I find myself having to learn something new almost every few years. That doesn't mean I have forgotten what I did before....and if a topic concerning my previous job came up in a conversation, I would feel qualified to add my two cents. This is what's going on with Choy. He knows about the RC, and has every right to discuss it.
Isn't this supposed to be a discussion? Not everyone will always agree....but, we should hear everyone out.