Anti-terrorism Law misuse

Glenn Greenwald partner was detained in London airport for 9 hours under an anti-terrorism law. Whatever you think of Greenwald or the NSA revelations it is pretty clear that his partner isn't a terrorist.

I'm actually surprised they used this law for all the bad press they will get. It's not hard to find some reason to hold someone for a few hours at least for something at an airport.Why use an anti-terrorism law when it merely shows how it is being misused ? Bizarre. What did they think they would get? They also nicked his laptop, phone etc