I personally think these folks fall into two nroad categories:

• If they're a hardened fascist ideologue then you don't want them in Ukraine because they'll be more dangerous if they come home (and that's usually more likely if they're joining out of principle and not self-harm).

• If they're not, they're probably an alienated doomer stuck in the reactionary pipeline that lures people into suicide-by-combat, which is not good either but less risk if they were to return. Not everyone in this bracket is necessarily a reactionary, either.

Idk I see the appeal of "let 'em become mulch lol" but if there's any doubt in the minds of someone you see talking like this, it's better to try bringing them down for sake of keeping another person out of that needless war. Starving Ukraine of meat shields no less a worthy cause in itself!