The closest troops to do that were Chechen troops.
Eh, how do you work that one out? Chechnya is 600km from Rostov. Rostov is a staging post for troops going to the front and a major logistics hub, so Russian troops were already there. Rostov is only 90km from the Donbass with tens of thousands of Russian troops and it looks like Wagner forces drove straight through them from where they were fighting around Bakhmut to get to Rostov. Could that be why the Chechens have been invited?
Right now there are local citizen reports that Wagner have crossed the last obstacle, river, between them and Moscow.
Would that be the Oka River? The one where the BBC has just shown a video posted by Russian authorities on Telegram showing tens of HGVs blocking the bridge in both directions? That river? The one not yet crossed?
MSM so far behind the times eh, or just the fog of war?
However, I do agree that it looks like the Russian forces might be playing a watching game to see how the dice falls. I guess that many of them are conscripts and do not want to be part of the "special military operation" so don't give much of a stuff.