I just saw your latest...while I'm still in the terror camp, the one arguement that is most persuasive against it is that the perp(s) seem to have a great knowledge of the "local" area(s). Something a long-time resident would have -- they know access roads, have an excellent knowledge of escape routes. That argues for someone who's intimate with the area -- even tiny, isolated towns like Ashland. They're obviously not using the Interstate (at least for more than a minute or two immediately after the shooting).
Now a lot of that could be explained in the terrorist camp as well: GPS, a deep-plant who's been here for some years planning this action, etc. But still, this person(s) has a remarkable knowledge of the area.
In some ways that could work against a local ---they'd be more likely to slip up. Someone would recognize them, notice they did something out of the ordinary. Using a small town might not work because often in those everyone knows everyone and everything. They notice when something is out of the ordinary, they notice even when a stranger comes into town. Escaping into a garage would be easier.
I think we have seen that sleeper cells could have been here for many years or even have been American born, as were the the ones in Buffalo. In my opinion this does nothing to diminish the possibility of terrorism. The last time I was in the Washington DC area was probably about 14 years ago and even then I was overwhelmed by the number of mideasterners there.