It makes sense to stop the guy in his tracks. Avoid a possible altercation. How many in the march are there more as anti Jew than pro Palistine?
It's just like football fans being segregated.
It only takes one person or a small majority of idiots to start.
The police took the correct decision. And, yes, I believe if a Muslim tried the same thing during a pro Isreal march, the police would do the same