I suppose people will still doubt him in the absence of legal paperwork (and I get that, honestly), but these comments from 2011 make me rest easier, personally:
"One of these days, maybe five years from now -- I hope it's 20 years from now -- the Bills will have to have an ownership change," Gundlach said in a followup interview with Channel 7.
"I think it would be a tragedy to have the Bills go to some random city and be called, you know, the L.A. Multitude or whatever the hell they'd call it. I want them to be the Buffalo Bills. I want Buffalo to receive a championship one of these days."
http://bills.buffalonews.com/2014/07/09/sources-jeffrey-gundlach-exploring-bills-purchase-approached-jim-kelly/