You didn’t get it straight, that is just how you interpreted it.
A game marketed as a WW2 game set in the European theatre of war, should try to accurately reflect the number and/or types of units used there, and not introduce units from a totally different region or made up solely to meet some agenda/checkbox/criteria. But there would be no problem if they then introduced maps/battles from other regions with other units or storylines for those. (I.e an expansion for a “European Land War game” could be for example, Tobruk, even though that would still be mostly euro powers fighting…)
Same as they could have the entire game set in one of those regions to begin with and used the correct units for that theatre.
Or they could just have it all made up, marketed it as that, and just do whatever they want.