For starters, the Pac-10 never "said as much when Baylor was floated", because Baylor was never floated. You just made that up. Just because the Texas Legislature would have liked to have seen Baylor hitch it's little green wagon to the Longhorns, that doesn't insinuate that the Pac-10 wanted Baylor. Baylor isn't a "Tier-1 Research Institution", and Larry Scott and the Pac-10 weren't about to let Texas dictate to them who the Pac-10 wanted. Baylor doesn't get to invite themselves, and neither does Texas get to invite Baylor. Only the Pac-10 gets to do that.

Second, in a different decade if those leagues had expanded the cougars would have still been left out. For example, in the late 1970s, the Pac-8 expanded....and left out the cougars. In 1990, the BigTen expanded....and left out the cougars. 1996, the Big 8 expanded....and left out the cougars. In 2011, the Pac-10 and the BigTen expanded....and left out the cougars. In 2012, the Big 12 expanded....and left out the cougars. Do you see the pattern here? It doesn't matter what "decade" were talking about. The cougars would have always failed to have met the requisite standards for admission.

P.S.: The "modern era" is NOW! Not sometime between 1972-1992. That whole "modern-era-started-with-Lavell-Edwards" thing is just "uneducated" cougar folklore.