Best not to over think events as they unfold, that just leads to conspiracies blooming. As it stands, Wagner is moving into Rostov if they haven't already seizing the city. It's a long running public dispute with the Russian MOD that goes back to events during the Battle for Bahkmut and came to a head with the recent attempt to force Wagner to sign under the Russian MOD.
The reason why this is so improbable is who is supposed to gain anything in this? What does Prigozhin think he is going to achieve with this move?
Most importantly, Where does Wagner get their supply and logistics from? I can't imagine they can take care of it by themselves so how long can they even last?