moving away to uni is a big emotional upheaval, and amongst all of the madness of freshers week, some people have a sudden realisation of all of the change that is happening around them.
This happened to me and im sure a lot of others but I stuck it out and everything started to fall into place and I began to settle into the whole new lifestyle, which is easier for some than others. Try telling him this, I'm sure he will be fine eventually, he seems like the kind of guy who will make friends easily anyway.
ah and also lets not forget that the upheaval is being made 10x worse by the fact that hes moved away from you...