Paper Tiger
a) one-way ticket
b) no checked bags
c) no destination adress
That guy looks very much like a business traveler to me.
One-way-ticket because I don't know how long I am going to be there (assuming I have the necessary documentation). no chekce bags. Handluggage does the thing (I can live several weeks with hand luggage only provided someone give me a possibility to clean my clothes). No destination adress. No, since I have no idea where they are going to put me.
Or he is a pilot going to pick up a new airplane.
Pretty difficult to spot the 'terrorist' from all the legitimates with similar tickets.