Trying to prioritize some religious groups over others in immigration is discrimination.
Yes. Yes, it is. And I can see how that instinctively sounds wrong, even to me at first.
But there are some very significant points to consider.
First and foremost, I don't know that discrimination is even avoidable when any community decides how to deal with immigrants. There are barriers not only of cultural values and opportunities, but even of fairly neutral and objective elements such as languages and the proficiency in those languages. It is a simple fact that people are treated differently and have different opportunities due to their accents, let alone proficiencies.
And Muslims, it must be acknowledged, are notoriously prone to want to keep themselves apart of non-Muslims, so much so that Hindustani (the main language in India and the official language of Pakistan) exists in two forms using two entirely different scripts: Hindi and Urdu. In that sense they are indeed noteworthy and it might not be much of a stretch (if a stretch at all) to say that Muslim migrants are discriminated in non-Muslim communities mainly because they insist on discriminating themselves from their hosts.
I wish I was exagerating.
As for 40% of Muslims in the UK wanting Sharia, you could also write that headline as 'The majority of Muslims in the UK oppose theocracy', but that obviously doesn't jive with the narrative suggested in the original post.
Yes, you could. It is interesting to wonder how come that majority doesn't seem to be very visible, though. I have my suspicions.