I think if you read the fine print it says that the chart is for 55 - 105 seats....how many seats do these aircraft have....I think they all fall short of the 55...Notice Pinnacle only shows there 900's which they only operate a small percentage and not the large number of 200's they have. (Nothing against Pinnacle, I'm just familiar with them);)

But why specifically exclude these aircraft?

they weren't excluded, I just haven't gotten around to building the study to include all of the regional carriers. I plan on including them on the next issue this winter.