But where the rubber meets the road is when they got a warrant to detain him on the grounds of his being a flight risk (which was utterly ridiculous if he didn't have a passport, and they were already allowed to carry out surveillance).

The guy was actively investigated - it's not like laws could be passed which are going to bar the FBI from investigating people who potentially are linked to major terrorist attacks, and doing things like asking co-workers, old neighbors, etc about them - or looking up court documents (which would show he was the lawyer on the cases he was on).

Which is my problem with the article - trying to frame this as a data collection issues is absurd. It's a procedure and institutional culture issue, and the big question is how a detention warrant was granted on such flimsy evidence. By focusing on a nebulous data collection issue, we in fact miss the important lesson and we're unlikely to change the part which has direct, real-world consequences (side note: 2 weeks detention is the same amount of time Australia's 'anti-terrorism' laws allow the federal investigators to detain you without notification or charge).