Back on topic - I know him. He is clearly not 100% and anyone who met him could tell that instantly. While I never heard him spouting missionary things, if he had no one would have given him the time of day.
I highly doubt that:
A) There was ever a yayin nesech issue with him ( I doubt anyone would let non-mevushal wine near him even without knowing this)
B) If he would have tried convincing people to convert that he would be at all coherent and have even a minuscule chance of being taken seriously.
He was a shlepper and an oddball, hardly a 'member of the frum community'. I don't know if it's accurate to say that he 'davened' at a particular shul. More accurate would be 'he stood holding a siddur on the wrong page and stared around waiting for the kiddush'
Interesting that YWN has now removed the article.