If the approach flown is 2D APCH (LNAV only) to the LNAV (only) minima - which I suspect you do say so - I do not see why that would be forbidden or what's wrong about it.
As long as you calculate the corrections and observe them, using the applicable techniques for the different FD guidance modes, it makes no difference IMHO. V/S, FPA, VNAV (FD mode). Can you do VOR overlay with LNAV-VNAV FD mode, assuming corrections are made to fixes and minima? I'd say yes and would not see 2D APCH (LNAV only) to be any different.
Some reservations however about the wiggy's quoted "no cold temp corrections required to the coded vertical profile on 2D APCH (LNAV only) if within ISA-25" (hope the paraphrase is not oversimplyfying). I am loosely aware there are some cold temp considerations in the design of 2D APCH (LNAV only) procedures, but still:
HEGN-temp_VNAV.JPG
This page has 3D APCH (LNAV+VNAV) constrained to ISA-10. The above mentioned guidance seem to suggest that it would be acceptable to shoot 2D APCH (LNAV only) with the indentical
profile uncorrected down to ISA-25. Does not sound in tune.
In practical terms that is if Egypt freezes over, I know.
