Drafting your population when you have a foreign adversary dropping bombs on you is the right thing to do. It is known as self defence.
"Self"-defense? The state is not yourself, nor is it a person. Defending the state is defending the power, structure, and organization that exists in the country. Which is only a worthwhile endeavor if there is a significant difference for the average person between the two sides.
If a state is actually good, if it actually improves the quality of life of its people, then sure, it's worth defending. Conversely, if a state is genuinely exterminationist, like the Nazis, then even a flawed, bourgeois state can be worth defending. But every major conflict since WWII, from Vietnam to Iraq, has had people trying to justify it by comparing the other side to Hitler and the Nazis, generally those comparisons are frivolous.
Ukraine and Russia are both capitalist states. What tangible difference will there be if one side winds up governing the disputed territory instead of the other? It's just a question of what color flag they look at while they get exploited. Is that worth sending people at gunpoint into a meat grinder? Is it a leftist, progressive position to say that it is?