You're right. Not all muslims are south asian or arabic. Lindh wasn't really a terrorist, though. He was a Talibunny.
A few of the terrorists don't fit the profile of arabs or south asians. But easily 99% of them do.
So it's silly not to concentrate on them. I'm tired of seeing great-grandma get wanded at the security checkpoint while the guy speaking arabic waltzes on through.
I feel sorry for the patriotic arab citizens of this country who will feel the brunt of any profiling. Yet I'd feel even sorrier for them if a terrorist killed them.
And that terrorist is almost surely going to be an arab or a Pakistani.
I don't disagree with the fact that most of them are Arab or Asian, I am only stating another way to effectively screen for possible danger.