If he is not checking luggage, just have him check in 24 hours ahead of time and print out his boarding pass at home. It's a bit quicker - then just go to security at the airport with that and his driver's license.
If he is checking luggage, I'd still check in at home (or on your smartphone, whatever device). At least at BWI there are two lines for checking luggage; one with boarding passes in hand and one for those who didn't print them. So it may still be a bit quicker to print the boarding pass at home.
No worries, if he doesn't have the boarding pass. They can just look up with his drivers license and flight time at the airport to retrieve his reservation.