I don't think geography has been ignored. The only reasonable reason, IMO, Lamar is not invited is Lamar being in the west.
But that logic don't allows jive with the Idaho invite, even being as a football only.
Yes, the balance division hole is in the east. However the Houston/Beaumont hole is west. Which is more important in the short term? Southeast Texas is bigger than 3 SBC states with 2 teams in each. Lets not ignore that fact.
You think Idaho as a football only is a big deal? 4 teams will travel to Moscow each year, that's it. South Alabama flew to Hawaii last year and Arkansas State flew to Oregon. Flying to Idaho every other year (if you're in the West) and every 4 years (if your in the East) is not a big deal. If you were flying all sports there then it would be.
Idaho was added because the Sun Belt didn't want to add more FCS upgrades because as of right now 1/2 of the teams in the league will be a recent upgrades. Idaho gives them an already FBS team which has some name recognition (however minimal), also Idaho and NMSU both offset the non-fb schools UTA/UALR which helps reduce travel for the schools in the West in all sport other than fb.
Fan of the Big 12 Conference, the Mountain West Conference and...