As noted already, this is not unheard of with award tix on CA and it is likely their fault. Though UA likely should have known there was a problem when he checked in at ORD. I'm glad to hear CA got him on a flight finally and hope you guys have a great vacation. If he writes to UA with a concise explanation, they will likely offer some miles as a customer service gesture.
btw, if returning on an award, it would be a good idea to check with each partner carrier and confirm he is ticketed. That's something many of us do as a matter of course with partner award tix.