Guess I'm about as nutty as you because that's what I first thought about. Maybe it wasn't supposed to go off, period. Warning, diversion, fear, etc. etc.
Oh it was supposed to go off, I think it just failed. Because supposedly(Now I have never been to New York so I don’t know how busy Times Square is that time of night) there were thousands of people outside..so that would have been his time to do this, but it failed, either it failed or he chickened out when he saw the cops checking out the car..Now, we have to find the guy because either he is working on his own and thought of this by himself or he is working for a much larger group
Now, somebody reported acetylene bottles in the car. That would work. But that's still amateur hour compared to real explosives like TNT or PETN that are perfectly within the manufacturing capabilities of a real terrorist organization. If the bomber knew how to make a reliable trigger, then he'd know how to make real explosives too. His choice of materials marks him as a lone wacko.