They are forced. They fight against the Ukrainian Army for their survival, because being drafted means they will probably die at this point. If they could keep avoiding the army, they would probably survive until this madness ends.

You can have your side on this and think Ukraine is fighting for survival, but that's a point of view, an idea. Some facts are:

1. Ukraine is currently loosing this war. It's even territorial.
2. Ukraine is loosing support from their allies. And if Trump wins, which is somehow plausible, they'd be practically alone.
3. Recently drafted citizens are just that, they are not soldiers. With their morale, they probably aren't even fighters.
4. A good chunk of the remaining Ukrainian people don't want to fight no more.
5. Drafting more inexperienced citizens will at best slow down the course of the current events.