I have heard this argument from multiple sources regarding this event but it seems to be based on a misunderstanding of how things like this work, so I strongly disagree. I've been trained on similar situations, and I know the escalation of force procedures in general (DC police are weird sometimes), and the second they saw Turkish nationals punching and kicking old men and women on the ground is the second they should have been escalating force. No, lightly tapping a dude sucker punching a woman on the ground with a baton on the back is not good enough. Sorry, but it simply isn't. I've been beaten worse in fucking training scenarios as the protestor.
Again, the real issue here to me is the lackidasical way in which the DCPD responded. IF they were afraid to enforce the law outside of the embassy there is a much bigger problem here than people are talking about. The same thing works for Americans in embassies abroud. They have a close relationship with and work with the host countries police and other forces... but they are notoriously well trained to not engage beyond embassy perimiter unless absolutely necessary. The fact that you think we should be afraid to enforce the law on Turkish nationals outside but close to their embassy says to me that if you are right, that embassy needs to be shut down, but in general I think you are wrong.
Now, I'm not a cop. I used to be a knuckle-dragging door-kicker, not a fat mall cop like most of the pd in the video look like. I don't know exactly what the pd's should have done, but I do know what they did wasn't it.
To put it another way. If American DSS (Diplomatic Security Service) showed up in England escorting Trump near the new US embassy, and the DSS rushed British protestors and just start fucking them up, I would fully support and expect the Brits to have arrested every single one, wait for diplomatic immunity to be verified (or not), and then proceed accordingly (persona-non-grata for those with, arrest and charge for those without). What I would not expect is to just let DSS walk back to their embassy as if they hadn't broken a dozen laws.