I've been in positions where I'm hiring people and where I'm selecting someone to rent my home to.

In both cases, there were people who contacted me who I could tell fairly quickly weren't going to be up to par with some of the other applicants. But in the interest of due diligence, fairness and consideration my response was generally
"Thank you for your interest. If you send me a complete resume (for hiring) / application (for housing rental), I'll review and consider it. I do want to warn you that there has been quite a bit of competition for the position, so please don't make any plans until/if you hear back from me"

I'll be the first to admit that maybe it would have been more expedient for everyone if my response had been "Listen dude, some (or most) of your grades suck and you don't have a good reputation among the field. Plus, you've seemed really unprofessional and not reliable in our brief interactions. Frankly, we'd probably just leave the position open before we'd hire you into it. Don't waste your time or mine. In conclusion, you suck and we don't want you. Have a wonderful day"

But that's just not how society works in the US. Turning BYU (or any other school) down will probably be done politely and with legalese - "While you presented yourself very well, and made a strong case for invitation to the Big 12, we've ultimately decided to not move in that direction at this time" is a lot better than "We looked it over and decided you're garbage. Go **** yourself." specifically because there might come a time when they do need BYU.