It makes sense. Not to be rude or unreasonably critical, but Boulder is a town with an attitude, a bit snobby. The people have their noses stuck way up in the air, and they all seem to walk around (or run around) with a very high sense of self-worth. Yes, the area, the mountains, some of the trails are very attractive - the people are attractive mostly if you're stil in your 20's and single and enjoy the nightlife - that's great, there are some lovely people. But after many years of living and running and working in Boulder, it has changed dramatically. Much more traffic - people, cars, tourists, students. It's a lovely environment, but the people quite simply give it a well-earned BAD reputation.
For instance, and I'll just make this last comment and leave it at this one example - CU's outdoor track (Potts Field) is basically off limits to the public, except at rare, unspecified hours of the day which is usually unaccomodating to the running public - Should it be that way in a "great" running community? Why so restrictive? Will the track be damaged? I don't think so. It's just a small example of the general attitude in Boulder.
I can't blame Mottram for not wanting to come back.