Does this mean a sign and trade is now off the table? He can only go to either Cavs or another team that has salary cap space?
Picking up the option would have made sign-and-trades impossible (since he would be under contract)
This makes a trade (outside of a sign-and-trade) impossible, but he can still sign with any team that has cap space (or the Cavs, since they have his Bird rights), or be sign-and-traded to any team not over the tax apron (since a sign-and-trade hard caps you)