It doesn’t matter? This incident was doubly antisemitic, preventing someone from protesting because they are Jewish, and assuming that pro-Palestinian protesters would attack them simply because they were Jewish (ie equating Jewishness with support for Israel and criticism of Israel with antisemitism).
Yes, he’s a provocateur. So what? If the copper had said it was because they wanted to keep the two groups of protesters apart (as they routinely do, or are supposed to do), that would be fine. But he decided to be racist about it instead.
I don’t know which jurisdiction you’re in but, while it isn’t illegal in the UK, you’re absolutely right about it being a bad idea and you are correct about the reason. In the event of a crash, it could count against you (in the UK, at least).