hehe - interesting way of putting it.
I guess as A-Team (and I am STILL not flying with any crazy Murdock) is an action-adventure morality play that takes dramatic liberties, so does MiaHM.
The thing about MiaHM is it's political allegory and I think some of the technical points are done for expediency.
though I do find it a bit strange..heinlein was a naval officer.....that'd he miss some things
the problem with Luna is it'd be more of an installation than a colony.
unlike a colony that is resource rich (which is why you'd colonize) and is independently viable (indigenous population is a good indicator if it can support itself in basic living functions), the moon is maybe more like midway that has value, but it's independently viable. Luna would probably act more as a facility with need for re-supply, tours of term-employment and so forth.
but I think Heinlein is taking that liberty to move the story along as political allegory as he may very well be doing with the technology (both in kind and in asymmetry) to move the story along.
sci-fi often employs very 'speculative' means as a narrative device (and the piece was written mid-60s how hard the SF is..welllll -- as SF has developed we've seen distillation into sub-genres with the hard getting hard)
Starship troopers had FTL to move the story along
Stranger in a Strange Land had Martians
again, to allow for the commentary of the theme...they are devices in the literary sense rather than the utilitarian sense
take another author's work, Dune, also a socio-political allegory - with magical spices and made up ecosystems (not a criticism, they are narrative devices)
I think with all these guys. Like Pournelle, we have to distinguish between the fiction and non-fiction writing
Mote in God's eye : fiction
Thor proposal : non-fiction
the technical problems of a narrative device in even hardish SF reminds me of the chant : the ringworld is unstable, the ringworld is unstable!