There was an interesting theory posed on Reddit (I sneak back there to lurk) that was a bit condescending "I am very smart" but I thought the central premise was actually interesting: this was all an elaborate way to desert since the rumor was they might get absorbed into the regular army and/or not get paid (or maybe they wanted to be assigned to an easier job back in Africa but got threatened so this was their work strike). They had to do it as a group because, individually, they'd have no negotiation power. The feint on Moscow was a show of force to get paid off. So, there was a van packed full of money that was somehow lost and found again in the middle of all this.

That's why the terms are that they get the treason charge dropped and the ones who didn't join just become part of the regular army.

The ones who supposedly "go back" to their staging areas may conveniently melt away/scatter with cash in hand. We'll see if they make it, or get picked up one by one as they try to make an escape. It will be interesting to know what the head count ends up at whatever base or staging area they were supposed to go back to.

Hole in the theory is that they can't expect to just take the pardon and rejoin society without consequences or end up just going back to the front line again rendering the whole thing pointless (unless they just wanted the money, being mercenaries).

If the desertion theory has any credence, that's still good for Ukraine, as Russia loses a chunk of fighting force either way and if news of this deal gets out to the regular army, others may think about using this method of desertion ("Hey, it worked for those guys...") Either way, a squad or platoon can't desert without getting mopped up but a battalion or division deserting will have a lot of leverage.