My own harmonization theory of Rheinland (regarding the "screwed economy" vs "powerhouse" views) basically has Niemann as Wilhelm II (they even have reports of Rheinland having to pay reparations and taking loans from Liberty!), Pryde as Hindenburg and Rheinhardt as you-know-who.
Also, Jinx, have you ever actually roleplayed with the RM? They are actually even more fanatical than the Nazis, because they view their head of state as God, and are known as among the most disciplined and ordered militaries in Sirius. We hardly see any non-infested Rheinwehr officers in vanilla, and the whole infestation thing greatly complicates our ability to evaluate their loyalties, along with the limited sample size of defectors.
And Adrian is correct. A sizable chunk of RM character names, including my own and half of Adrian's defector, is taken from World War I or World War II Luftwaffe aces.
"Heil Rheinhardt" simply means "Hail Rheinhardt" in English, in any case. There's nothing strictly Nazi about it, unless you add the graphical ability to make a Roman salute. But, kind of a moot point, given Chapter 4.