He's going to get arrested by DOJ agents as he steps off of the plane.
Kidding. There's no problem flying them in. Literally no different than flying into most States. We don't have gun licenses, BTW, except for most NFA weapons, .50 BMGs, AWs, and for carry.
I'm not sure what the rules would have been on shipping his guns to himself. Might have been OK. I know stuff I send to 'smiths, even out of State, get shipped right back to my home. I'm not sure you need an FFL to ship to yourself unless you want to use USPS (those without FFLs can't use it to ship handguns). Obviously it's neither here nor there, at this point.
I've had my guns put on the carousel with the rest of the baggage as well as taken to the place where you claim lost or valuable baggage on different flights. The latter seems to be more common these days (might actually be what they're supposed to do across the board, and they were just wrong to put my guns on the carousel on those other occasions; I've only had my guns taken to the baggage claim office twice, ever, both the most recent times I've flown with guns). Whichever it is, he literally just gets his stuff and leaves (airlines require ID for the latter). Obviously you follow the normal rules for checking firearms.