Twin time is more just about managing two engines and having baseline knowledge of assymetrics and dealing with engine failures, turbine or piston is irrelevant. Having Turbine time ensures you know what simple things will kill a turbine. Turbines might be 'easy' to operate but they also have some areas where you can kill them rapidly with ham fisted no brain operation. On start you can cook them, in flight especially at altitude they are easy to cook, rapid movement of levers can lead to compressor stalls and spitting blades and so on. If your Piston or Turbine has FADEC or similar that is what makes them easy to use, not the type of engine.