It's a curious decision to use the amnesty on Bell, who is an expiring contract and wasn't really making that much money to begin with. The amnesty was put in place for teams to use it on a player with a big deal and a massive contract who was underperforming. Using it on Bell (who is making only a few million dollars) doesn't really free up cap space to sign a big-time free agent, and it wastes the amnesty for when it could be used on a bigger player who would really free up space.
The Warriors withdrawing their offer for Williams means that they're presumably going hard for DeAndre Jordan. Presumably both of these moves will free up enough space to get the man they want.
To discuss the situation with Bell, Williams, and the Warriors, head to Golden State of Mind.