I had a very nice dinner in Bozeman in 2003 while riding in the Iron Butt Rally. One of the other rally riders and I had recognized each other as we traveled along. We stopped, had a good meal, and then went on our separate ways on the way to Missoula and the finish of the rally.
If our numbers are consistent in percentage with the population in general, I'd guess you are quite right about not having many members in MT. Given the same percentage of MSTA members that are in some of the geographically comparable States, it would make sense. I have to admit that a sport touring bike is probably the best compromise for an area like that to be found. They're fast enough to get from one place to another without lollygagging, and yet, still comfortable enough to stay at it for long periods of time.