I do not think you have to have an AMA waiver if you are in AMA and want to fly turbines. The waiver is just that. It waives the usual restriction on AMA insurance from applying to turbines. There is no rule that I am aware of that says you have to have one to fly turbines. If that were the case then no one would be able to fly a turbine to learn how to fly one before getting his or her AMA waiver.