This is true - we don't know what's been discussed or what level of interest these conferences have in any of the Big 12 leftovers. The reason I keep talking about the PAC having interest in the likes of Okie St. and ISU is because value to a conference is as much about current financial health of the conference as it is the schools being considered.
Ignoring geography and looking at a simple TV viewership and fan interest (as a proxy for potential streaming value), ISU and Okie St. would have next to no value to the SEC, and little value to the Big 10. ISU and Okie St. would be in the 6-10 range in these metrics once this year shakes out. Would there be some interest potentially if Fox pushes the Big 10 to expand, the Big 10 is not successful in going after some bigger fish, and a couple of these Big 12 leftovers take a big reduction in media rights? Perhaps, but it would be quite a needle to thread, all to add a couple teams in that are roughly in that tier of teams that are nice to have - Iowa, Michigan State, Northwestern. These schools do bring value to the Big 10. But if they weren't already members I think there would be interest, but the Big 10 wouldn't be falling all over themselves to get these schools in.
On the other hand, Okie St. and ISU would be below USC and Oregon. Okie St., ISU and Washington would be that next tier in terms of TV viewers.
So I think there's value to the PAC. Part of that is the value of Okie St. and ISU being underrated, and part of that being the lower financial health and revenue of the PAC vs. the Big 10. I think something similar could be said with WVU and the ACC, but there situation is a little more complicated.