Firstly, I'm not talking on behalf of the police, I can have my own opinions. Secondly, the police have a positive duty to facilitate lawful protest, and the Supreme Court has ruled that disrupting traffic, depending on the facts of the case can be a lawful expression of protest - which is why the Government has needed injunctions. You may not like it, but that doesn't make them the violent criminals you make them out to be.
Whether it's the best thing to do or not, the obvious point is that protests such as these won't be stopping anytime soon, indeed they're likely to increase in frequency and change tactics to stay in the news and in people's minds.
I reckon my Grandads generation of Police men would've ensured ambulances could get to hospitals before worrying about lawful expressions of protest, it's honestly pathetic. This is the same generation of Police who watch statues being vandalised and thrown into rivers without intervening though.