What I'm saying is that given the little amount of coop content we have (not enough to keep him busy until SC is out, since that's his goal), there is no reason to not point him toward other content that might interest him.
Not pointing him in that direction would actually be a disservice both to him and the community, since he might not realize that there is so much he can play, and the community would loose another player thinking "that game is so dead, I'm out".
@lilsnippy: It is possible to manually turn most SP missions into coop missions, and although the balance may be affected, it will usually not break anything. The process is quite simple, and I can walk you through it if you're interested, although I can obviously not garantee it will work for all missions and campaigns.
Otherwise, if you want to play those SP campaigns with a friend, you can also do a parallel playthrough: using two screens and a streaming software to play the same thing at the same time and share your gaming experience in real time (ish, minus streaming latency). I'm currently doing that with the ME trilogy with a friend, it doesn't work too bad. That's probably the easiest way enjoy with a friend the huge amount of SP content we have over there.