This is a free country. They aren't obligated to do anything, it's not law.
I'm pretty sure you understand the question.
Are they protesting against the islam "law" that mandates woman to use Burqa or are they protesting against it making harder to identify people that could be criminal?
I would assume they are protesting against the Islamic doctrine. - But they tend to focus their hatred towards the Burqa specifically, either way, does it actually make a difference? They are being hypocrites.
Religious freedom is a founding pillar of this country, it is literally written in the constitution, so whinging about Islam isn't going to get them anywhere.
Wearing whatever-you-desire is also a freedom, if the Prime Minister can get around in public in his budgie smugglers, then people should be entitled to wear a Burqa.