Apparently here's how it went down:

"Look, if BYU had just gone Indy, whatever. It wouldn't have been a big deal. But it was so much more than that. Here's a quick rundown of what went down; BYU went Indy, and then tried to lure some of the programs in the MWC back to the WAC in order to cement long term opponents. And this was right after TCU and Utah left. Which would have left the remaining MWC schools in a similar position to what happened to the WAC. If not for the UNLV AD speaking up about it, schools like Wyoming and the other Front Range schools, would have been bent over the barrel. Hard. That, combined with generations of constant BYU fan arrogance, yeah."

And then another poster follows up with this:

"BYU wanted Fresno, Joser, Nevada and Utah state to go over. Utah State was all for it because they are BYU Jr., but Fresno, Nevada and Joser told BYU to **** off. and now BYU plays by itself like a loser for participation ribbons each year"

I was in a military situation where I wasn't exactly able to read about this when it happened, but if I remember correctly, the WAC tried to get BYU into the conference (sans football), and when the MWC found out they invited whatever WAC schools they could to keep it from happening, and when it didn't happen BYU went to the WCC instead.  I don't remember BYU ever trying to poach MWC teams to the WAC.  In fact, it wasn't until this happened that the MWC actually did what they should have done all along and invited Boise State.

Am I right and the Wyoming fans are just rewriting history to fit their hatred narrative, or was there more to it?