The OMA is very clear about lots of things.
Do you follow the cabin crew briefing to the letter covering every subject mentioned? Never venture away from 'THE CITY' on layovers? Never use or allow to be used PED's on the flight deck? Ever read a newspaper or magazine? Always take gear down at glideslope alive? (That's what the FCOM/FCTM requires and the OMA requires us to follow that unless otherwise directed).
Not wanting to get into a thread drift with this, or necessarily disagreeing with your viewpoint, merely pointing out that I know of absolutely nobody that can and has followed the OMA completely, to the letter, during my 15 years here. It comes down to how you apply it and whether you can justify it.
In regards to flight deck access, you choose to follow it. Fair enough.
Harry