I think you've missed the point about the incident?
You're right it's probably nothing to do with racism (but police do have a great record when it comes to this...not).
But if you're behaving like a clown in an airport, do you deserve to be kicked and stamped in the head while already restrained and seemingly not posing a threat?
If you're broken a female copper's nose (which is bad enough and should not be tolerated in any circumstance), then you should be arrested and charged and tried with that process. When you're down on the floor, Tasered already, not even facing the police, clearly unable to move or look to attack therefore the threat decreased significantly, do you deserve to be kicked and stamped on the head? I think not.
I don't get why there are religious-based protests either.
As for Anjem Choudary and no protests there, are you taking the piss ? They're two totally different individuals and circumstances. Might it have occurred to you that perhaps not all Muslims actually agree with him, and therefore see no reason to protest just because he happens to be Muslim too? Or are you saying that because he is Muslim, they should have protested regardless? Come on, man. That's such a bad analogy and example you've put forward.