Transparent trolling intended to cause people to criticize other groups of Jews. How sad.
On the miniscule chance that this is actually a true story the solution is simple: If you’re a friend of his, you can have a conversation with him. The fact that you would need the advice of an internet forum to tell you that is puzzling, but there it is.
If he listens to your advice, great. If he doesn’t listen and you feel uncomfortable attending, don’t go.