I bow to your wise council John. The Ops Manual in question ordained that pilots were to comply with all instructions issued by the authorities, but then has an SOP of requiring use of dud take off data, where does that leave the poor pilot in the event of an accident caused by the dud data. Not complying with SOP has its own issues if, you want to kick the traces. It's a rhetorical question, because I know what the legal eagles would say.
The conundrum may have applicability on the King Air, where as has been pointed out, on some fits (if using Hartzell props - is in limitations section), arming auto feather is mandatory (a no go item), but folk may not be using it for SOP reasons.
The Bangkok QF brought to light the airline was using a procedure as SOP that the manufacturer counselled against. Once again, where does it leave the poor sod in seat 0A. So many masters wanting satisfaction.