I am fairly sure there are swas- Uh, symbols like that on the steam workshop for other games.
Maybe, im not sure of that. Depends on Steam politic.
Steam could also decide to not sell soft in a specific country, and sell it in all the others.
Or sell it in a modified version. You may ask directly to Steam.
I dont know exactly about that, because in my country there are no restrictions.
Here all the expressions of historical symbols are lawful, expecially if them do not represent the personal idea of a subject but a representation of an historical events.
And wargame could be considered a form of historical representation, not the personal politic idea of the developer.