Get your facts straight. The Bills didn't fire all the coaches. They gave them permission to seek other positions. Big, big difference.
In order to hire any of them, Buffalo would need to approve the hire if it is a lateral move (same job description and title). Any team wanting to hire someone away without Buffalo's permission would need to offer the coach a better position.
For example, Bobby April is something like "Assistant Head Coach, Special Teams". Someone who wants to hire him would need to get permission from Buffalo to hire him as the same or lesser title, OR they would need to give him a better title, like "Chief Sycophant Assistant Head Coach, Extra Special Teams."
So people should stop pooping themselves.