Regardless of the outdated stuff, even just as a StarCraft player, a rush to Kiev would be failure as the distance would be too far to maintain and attacks from both the north and south in a pincer would easily cut off. It makes no sense.
It makes sense to secure the eastern portion, which has a lot of minerals, etc, fortify that, and then mine those resources as an expansion base.
They aren’t going after a bunch of farmland they know the UN will tend to anyways to feed the starving around the world. Russia already has enough of that