It doesn't have to be a large part of their workforce, just key important positions.
I'm Canadian and thus not affected by this directly, but I have worked in places where co-workers in important places came in as refugees from the affected countries, notably one co-worker who is damn good at his job and whom without him I'm sure there would be issues. He's not even Muslim himself (awesome guy, one of his favourite things about Canada is bacon). It would have sucked if he was suddenly barred from re-entering the country after being away from holidays.
How would YOUR organisation be affected if even 2-5 people in key positions happened to be blocked from entering the country for a month or three? Probably more than you think.
Add to that people who would be unexpectedly separated from family etc and it's really a huge clusterf***. The last thing you want to find out after being out-of-country on a business trip is "hey, you can't come back because the sh*thole you escaped from is now on a blacklist, even though you hate everything they stand for and that's why you left."