To offer a slightly different perspective...I obviously don't believe that "Muslim" is a race, but to many white-supremacist and Islamophobic groups it may as well be.
Islamophobic prejudices don't get applied to White or Asian Muslims in the same way as for Muslims from the Middle East, because people seem to be assessing whether they look like the guys they saw on the news. I want to, for example, bring up the case of an Indian software engineer from Kansas who was killed two years ago:
SO, the argument I'm putting forth here is this:
Muslim people do not constitute a race, but the people who are prejudiced against them (and those who physically attack them) often believe that they do. Using the word 'Muslim' as a weird synecdoche for 'Appears Middle Eastern' is common enough, and I believe that people who hate the nebulous group of 'Muslims' are holding racist beliefs against a race that they have misnamed, and largely imagine to exist.
In the case of Roseanna and Amy, I would guess that they have learned Ilhan Omar's name and may be vaguely aware of her nationality, but probably subconsciously conceptualize her religion as her race and act with according prejudice towards the congresswoman.
...Or that's how I think about it, anyway. Do you think I'm maybe not being fair? Honestly, there's a chance I'm assuming too much about Roseanna and Amy. Idk. The idea's out there, I'm curious what you think about it!