It was 15 months later that the SEC announced A&M would be joining, so I don't know how far along those talks were, but you can lose them in any case as OU and UT were the prize.
Look, it's clear the P12 didn't want Baylor, OSU and possibly TTech and time will tell how smart that was but consider this: a weak conference like the B12, one that lost Mizzou, Nebraska, CU, and A&M in the span of 24 months and replaced them with an outlier like WVU and a small school like TCU still generates more money than the P12 because of the strength of the OU and UT brands.
Don't kid yourself. You can talk research and academics all you want, but college athletics is a money game first and the first 8 years of the P5 era show that the P12 is falling behind. Adding OU and UT and whatever schools they insisted they bring along would have changed that drastically.