Was there actually anything stopping them before, other than some traffic cops with a grenade launcher, and some excavator operators frantically digging up the motorway?
It was a bad idea to begin with. Putin would and did flee to his bunker and then have to endure a siege on Moscow after that… There is no way they win a siege against the Russian army, in Moscow.
Died fighting whom? The Russian populace that he seems to support, and are apathetic at worst towards him? It’s not like Putin himself was going to lead the siege charge on horse back carrying an AK or something.