They swore to do as America requires, including attacking Poland and Serbia if needs be
Well, being born an American, I never had to swear to anything. :-P
And my ethnically Polish grandparents would loved to have been nationals of Poland, but they were Prussian citizens and it was out of their control.
My German grandparents were also in a situation beyond their control. They volunteered to come to Poland to help drain the swamps and in return they received land. They got along well with the Polish nobles, but then they were victims of the partitions and became Russian citizens against their will.
Not everything is about swearing allegiance. Nations often decide who you are whether you like it or not. My grandparents all came to America seeking freedom from the forced upon them nationalities.
When Poland became a country again, my great grand parents were still there and alive. So, technically, I could probably apply for a Polish passport as the rule says that citizenship can be passed down to someone like me, if they have but two great grandparents.
So, then.....would I be a traitor to the USA to do this? Or a traitor to Poland to ignore this option. See? Not all things are so cut and dry as you make it out to be.