The South Park thing might be the detail, but since he went to Paki months ago, for months, obviously he was coming back to do something, South Park or something else. He might have planned the NYC car bomb as a first round. Maybe he had other plans after that.
I heard that the guy to made online “warnings” against the creators of South Park was in the area at the time of the incident. New York Daily News story link:
http://www.nydailynews.com/news/ny_crime/2010/05/03/2010-05-03_i_was_in_times_sq__but_i_didnt_do_it.html