I agree that "I'm too self-absorbed to be in a relationship" is not really what you want to be hearing. It could either mean he's trying to warn me off, or that yeah, he is emotionally unavailable. I'm kind of hoping it's just the fact that he was telling me about a relationship that he felt he personally had made a mess of (he said "it was my fault", to which I said "it's not usually entirely one person's fault") and it was one-thirty in the morning and we'd consumed a couple of drinks and were getting a little maudlin.
He has just gone off on another trip for a couple of weeks but I am going to see if I can get him to take me out on his motorbike when he's back. If we don't get killed, it seems like there might be some potential there.