Well, there are other factors that play into these decisions- namely intangibles, quality of play in college, etc. Regarding Flynn's capabilities, I have no doubts that he is a good quarterback. But are there quarterbacks in the draft who have more potential and better intangibles? It is possible. It is important for the Bills to be diligent in pursuing all available avenues, but in the end I feel that it may be a better option to draft a quarterback and create a culture change in the organization. If we could acquire Flynn for a 6th rounder, I would jump all over that- however I doubt that the Seahawks would consider that fair compensation.
If you're going to make that premise, then why draft bother drafting a QB at all? None of them have any experience at the NFL level, after all