Boeing as mentioned above does hand out FCOMS that advise to deselect instead of switching it off. If only for low speed protection and G/A thrust. However they only do that if they have audited the training program of the airline in question and are satisfied with the training program.
All airlines I have had dealings with do not use Boeing FCOM but customise the generic Boeing FCOM to suite their operations so I would doubt that an unmodified factory FCOM will mention deselect.
If your airlines name is on the top of the FCOM then it is not a Boeing FCOM. However I have never seen a customised FCTM so that is really the unadulterated Boeing view of the world.