If that is all it comes down to, then yeah, I dont think he will try to take eastern Germany, no matter what he would like. Regarding the various attributions, I dont know what people you are talking about.

If protecting Germany is your final answer for why support the war, I think it is fine for the US to sit it out until article 5 is invoked.

It is kind of like expecting Europe to be ride or die in a US war with China over Taiwan.