Fallout New Vegas Help?

So today afterr logging almost 30 hours onto this game, i finally beat it. but i think it would have been alot easier with the solar strike gun that you get from the black kid in freeside, (the one that says "Reach for the sky mister),however, after I armed Archemedes 2 in the Helios tower and went to freeside to get the gun, the kid is nowhere to be found. i found the little girl (Stacy) that he was chasing with it but i cant find him. Usually when you enter the east gate to freeside, he comes running out immediatly, but now he doesn't. Did i do something wrong?