It's only burning a bridge if you have a chance to do something else with them in the future. And, since there are about a million small colleges with locations just like theirs, I wouldn't worry about it.
Because, let's face it... One of their alumniseesers comes to them with big news: (a) He's making a coolio movie with a coolio budget and (b) He wants to help support his alma mater and they reply with a big, wet, "Fuck you," then, well, fuck them. Because they'll sure be glad to contact you for money after this. Trust me. They'll come to you with hat in hand, and big puppy dog eyes. Oh, we'll be glad to put this in the alumni newsletter. Oh, it's so great you're doing this. Oh, please consider a donation.
Time to learn the difference between bridges and swamps, RC. A hard lesson for me, too.