Unfortunately, there are a large chunk of people who get sucked into the fear-mongering...and they aren't able to think critically for themselves, so there is no reason to expect that they will understand things like context of the situation much less the interaction of various groups of people.
While it may well have been a Muslim who committed this atrocity, people like the OP (and many other commentators on this thread) fail to understand that many Muslim doctors worked through the night to help the injured, and many Muslim taxi drivers drove victims home for free. The perpetrator appears to have been born and raised in the UK (initial rumors is that he was from Kent, but we'll need to wait for validation), but that won't stop idiots from claiming immigration is the real problem.
“Evil isn’t the real threat to the world. Stupid is just as destructive as Evil, maybe more so, and it’s a hell of a lot more common. What we really need is a crusade against Stupid. That might actually make a difference.” - Jim Butcher, Vignette