A constantly repeated argument in the West is that Russia's war of aggression against Ukraine is illegal under international law and that Ukraine thus has not only the right to defend itself, but also the right to ask other states for help in defending itself. This is indisputable, as this conclusion is based on the principles of the UN Charter. But does the UN Charter thereby also give the West the right to continue this war at will, to seek a military victory over Russia and to refuse all peace efforts on these grounds? Certainly not!
The West is not “continuing the war at will.” That phrase has no meaning in this context. The West is supplying Ukraine with the means to continue to resist the illegal Russian invasion.
The West would in fact have the right under Just War theory to enter into combat operations in Ukraine against Russian forces, and to operate combat operations against Russia up to and including invasion. Because Russia is the aggressor, Just War theory gives other nations the right to participate in the resistance of aggression.
The claim being that... Western powers are unwilling to see the threat in appeasing Germany (Russia) because they want to focus on the perceived larger threat of communism (China)?
If we're talking about the constant push for "peace talks" in Western media, no, they either want to focus on keeping the capitalism engine churning (instability is bad for global markets; small, manageable wars are fine, but huge East-West conflicts that result in huge sanctions aren't. Sanctions = less business), or they're seeking appeasement because they're right wingers who agree with the ideals of the aggressor (I'd make some comparison about being the "modern equivalent of Nazi sympathisers", but it's just Nazi sympathisers. Same old song. Putin might not be a Nazi, but he sure is a fascist, and he hates all the things Nazis hate).
Outside of the mainstream media you've got a grab bag of leftists who either reflexively believe that all global conflict can be boiled down to "War bad, peace good, therefore weapons for Ukraine bad, peace talks with Russia good", or who've conflated criticising Western imperialism (which, y'know, we absolutely should be doing) with the notion that ergo anyone who hates the West is the good guy. Usually equal parts of both. Plus of course, your alt-right types who love Putin because he hates the gays (see above).
He's asking how OP (and you?) think this is different from Poland in 1939. Regardless of whether or not you agree, do you understand the parallel being drawn?