Personally I wouldn't mind working with him as a fellow employee, but he'd make me nervous as a manager of a small business. He sounds like he's great at his job, but has zero emotional ties to it, which translates to him being less likely to weather any bad times the company may face.
Ultimately, you clearly agree that gaining and retaining great talent is what makes a software business stand ahead of its competition, so isn't it risky to gain someone who isn't going to feel bad about leaving the business (and take all his experience with him)? If I can hire someone who'll fit in well with the team and produce good quality code, then I'd consider him a better long term investment that someone who fits in poorly with the team and writes great quality code, purely because the latter person has fewer reasons to stick with the business than the former.
I'm not sure what kind of connection there is between being boring and being more likely to jump ship. Plenty of interesting people jump ship too, because the best way to become interesting is to accumulate a lifetime of diverse experiences and staying in any one place gets in the way of that.
If you don't want people to leave the business, earn their loyalty. A boring person still wants to be treated fairly. They still want to take vacation, even if it's to visit their boring family rather than go backpacking in Tibet. They still have the same capacity to either enjoy or hate their job. They just don't necessarily have an interesting answer to the question "any plans for the weekend?", and I don't see why that makes them worse employees.
I'm not sure we mean the same thing by 'boring'. Boring, to me, doesn't mean that the person doesn't have hobbies, rather it means that the person is a perfectly nice person who just doesn't gel with the team. In fact, 'boring' is probably the wrong word here: it should probably be something closer to 'outsider'. That said, larger organisations do depend upon outsiders to prevent groupthink, so this is a multi-faceted issue.
Ultimately, you clearly agree that gaining and retaining great talent is what makes a software business stand ahead of its competition, so isn't it risky to gain someone who isn't going to feel bad about leaving the business (and take all his experience with him)? If I can hire someone who'll fit in well with the team and produce good quality code, then I'd consider him a better long term investment that someone who fits in poorly with the team and writes great quality code, purely because the latter person has fewer reasons to stick with the business than the former.