There's a lot going on here...but it's apparent that Rosen is being treated as a proxy chip in a political debate. That and apparently one's support or rejection of Trump has anything to do with Christianity.
I expect that McBeane want hard working professionals who aren't lockerroom cancers. An NFL team is a large group of folks, many of whom lean left, and many who lean right. I don't think his politics have anything to do with the Bills' evaluation of him.