If he brought up ISKON, you could have brought up Missionaries /Evangelists. Those are entities who can be criticized. Religious prayers of any religion are out of bounds. Hope you understand the difference. Peace.
SO you want me to set my standards by the low standards of a Bigot. Sorry, no can do.
I do not play to give a measured response to a hater. That might be your desire, not mine.
It would have been more useful if you had spared a piece of advice for the very person who you have supported. In absence of that, your 'advice' holds no value in my eyes. You are guilty by association and by tacit silence.