I love Middle Eastern food. Where I live now we don't have any such places, so I miss it. I've had a bit of everything, shwarmas (spelling), Lebanese Pizza (seriously addictive), humus, fallafels. For me culture exposure always starts with food.
There are many who want to come to America and Canada to flee the crazies in their own country. If they embrace American values, it's not my personal business how they worship. If they work hard, contribute, open businesses, stand for the anthem and love their country, they are just as valuable as anyone else.
Of course, just saying "we need or want people from a particular region, just so we can be diverse" in my opinion is a horribly insulting method of performing the function of immigration. He came to America presumably a normal guy, he was working, doing what he needed to do. He was radicalized in America. So the who, what, where, when, how needs to be asked and answered. Why did he go off the rails when so many others didn't?
These radical extremists have to be identified and dealt with, easier said than done.