How do you know they're Iranian? Most Middle Easterners look the same to me…
I wouldn't 'think' that, as I don't see such people as those who would bomb me. I don't have such prejudices against them. I don't actually, contrary to my tongue in cheek statement above, ever use racist abuse, even when I'm on the receiving end of it myself. Just not the way I think.
I would use someone's weight as a weapon though. I'll admit that. It is still allowing my prejudice to colour my actions though, and is by that fact, wrong.
If the line is in your head, maybe you need to question how it got there.