There is no standard of saying or not saying things that you can meet that will convince one of these kinds of guys that you're not "Israel First" once they decide you are, and any attempt you make to try to correct them will only make them angrier and more obsessive.
As far as I can tell, he hasn't publicly voiced Israel first opinions
By virtue of being jewish he doesn't have to. It is intrinsic to his existence.
There is no standard of saying or not saying things that you can meet that will convince one of these kinds of guys that you're not "Israel First" once they decide you are, and any attempt you make to try to correct them will only make them angrier and more obsessive.