PA does allow open carry but I think there are some restrictions re; motor vehicles, age, etc.
As noted, Handgunlaw.us is a good source. Another choice if you or your armed son travel often is the latest
www.gunlawguide.com edition(2014).
I'm not a lawyer or a sworn PA law enforcement officer but I
think you can't transport loaded firearms in a motor vehicle(open carry) without a valid CCW(either from PA or a state PA recognizes).
If your son is under 21 or does not have a CCW then he might not be able to travel with loaded handguns.
I'd add that PA state laws
do not have any restrictions or laws re; college campuses/university property.
In 2013, I went on the property in CUP(Clarion) & IUP(Indiana PA) with no problems. I had my M&P .45acp compact in a SERPA.
FWIW; I think PA allows active duty & reserve US armed forces(under 21) to carry concealed with a license. Other US states have military laws too for service members who want to carry a weapon on leave or off duty.