I have just seen a video of the policeman confronting the person concerned which was shown on the news.
And what this looks like is a hamfisted attempt to tell someone to avoid a group of people that may be hostile to him ie the policeman is saying the demonstraters could or might be a threat to someone "openly Jewish" and adds I am not accusing you of anything.
I suppose this would be the same if they advised someone who was "openly Asian" to not go near a National Front march.
This is standard policing, lone police taking it upon themselves to decide that to avoid a confrontation or violence they advise individuals to avoid areas where a demonstration is going on. Its happened to me. I assume because they think a lone female is vulnerable going near where opposing groups of men are confronting each other.
I am not saying the policeman was right, and the phrase used is unacceptable, and also stupid as "openly Jewish" people are on the march.
For me this is the poison coming from some sections of the political class eg Suella Braverman who tried to whip up fear about the marches not being safe, even though Jewish people take part in them.. Or when she went totally batshit and implied one of the marches was going to disrupt the Rememberance Day events, although the march that day was no where near any of the ceremonies. But what she did do is encouraged right wing thugs to turn up looking for a fight, which never happened, so they fought with each other. Or the politician who talk about no go areas in London.
Apart from the bad policing it is also disgraceful that the media, well some of them, are trying to skew the reporting to make out it was something it clearly wasn't.
Or individuals jumping in and saying it was a set up.