about how the Utes acted when joining the Pac12 was that they completely forgot their history overnight and became snobs. We and they spent too long beating the drum of the excluded team due to a conf. affiliation and lack thereof. The other reason is simply they are the only fanbase I've ever seen anywhere in the country that does this. I've never even seen an SEC, B!G, or ACC sticker (even though I lived in a couple of those). Anytime I've seen a team sticker, if it includes the conference symbol at all, it's much smaller and secondary to the team logo.
Of course BYU will fly conf. flags at the stadium and other venues on campus along with those of other teams in the conf. That's the appropriate and traditional place for them. And of course people reserve the right to do whatever they personally choose to do. I also reserve the right to groan and roll my eyes in embarrassment if/when I see it.