Threat profiling involves many aspects such as country of origin, ethnicity, religion, traveling habits/patterns, etc. If you meet a certain profile, one should never be allowed into the U.S. and certainly the privilege of traveling by air should never be granted.
It's funny but some of you guys still can't agree if flying is a privilege or a right.
If someone meets that profile but is not a terrorists but is deined the, as you state it, privilege to fly then what must that person do to visit our great country. The government system of making list, well it, it sucks. Innocent people will be affected in some case by their race, religion and travel habits.
As for the Lindh nutcase, he converted to Islam when he was 16 and in 1998 he began a 1 year "holiday" in Yemen, hobnobbing with fellow Isalmic radicals. He was allowed to return (under my proposed system he would not have been allowed to enter the U.S.)
Did they know this before or after he returned to the US? Hind Sight is alway 100% but its the present that we need to know that we just don't always know. So your threat profiling idea may keep some out but if we don't know anything about the people before hand then how can assume their a threat?
Do we just not allowed certian races, religions or people with certian travel habits to enter the country, even if they did nothing wrong?