HC - then you start to get into a rather fatuous argument like - does it say you can't fly backwards at 50kts? no, therefore it must be OK.
Spot turns are hardly a well documented, hazardous regime of flight (aklthough with some students I have had that might not be so) whereas flight in FP is. If your pilots want to go and fly in FP, let them and see what their viewpoint is when (if) they get back.
At some point you either have to force the manufacturer to amplify the limits in the RFM or, as you have done, make a clear policy decision not to fly in FP.