In what way is this distinction relevant?
Are there numbers of Pakistanis in UK who aren't Muslim?
Pawkee-stahni is too specific, muslim is more generic.
Not all bearded barbarians are Pawkee-stahnis but all Pawkees are bearded barbarians.
There are non-Pakistani Muslims in UK. The initial wave was mainly from the former British colony of India (which divided into India and Pakistan). Now UK gets immigrants for lots of Muslim countries.
Because the fact that they were Muslim is more telling than the fact that they were from Pakistan - because even if there are only precious few Pakistanis in the U.K. who aren't Muslim, it still deserves pointing out that aren't just "from another country," but "Muslim."
Imagine reading a report that a group of youths - "two Egyptians, one Sudanese, two Saudis, and three Indonesians" - had been arrested for carrying a bomb into an airport. And let's observe that they also had "religious leaflets" with them. According to your logic, it wouldn't be relevant to instead report that eight MUSLIMS had been attempting to smuggle a bomb into the airport (since virtually all citizens of those countries are Muslim), and that they had been carrying leaflets calling for a "worldwide djihad" (since that can almost be taken for granted, given the first item).
Regards,
What woke them up?