https://en.m.wikipedia.org/wiki/Boise_State_University

And the first thing on their "About us" section of their website specifically calls them out as a research Institution as well.
https://www.boisestate.edu/about/

Glad to know you think Boise is also an elite research institution.

It's a matter of tiering. Literally every R2-tiered University uses a similar description - whether that's Boise St, Northern Arizona, Wright State, Idaho, Idaho St, or Wyoming, they're all listed as research universities because they all do some research.

And nobody is arguing that. BYU certainly does more research than Grand Canyon University or University of Phoenix or UVU. But they also aren't in Tier 1 for a reason and it's because that isn't the chosen focus of the school. Which is fine! They don't have to be and don't particularly want to be. But it does mean that schools/conferences who value high research output may not be as interested.