I have no idea on balance of trials vs negotiations of course, that's just speculation. But the logistics/personnel issues are far better established. I mean you only have to look at the events of the past couple of weeks to see that... No, I'm not about to argue that everyone is wandering around with Mosin-Nagants, and that all the tanks and artillery are gone. But there are resources Russia can't replace through conscription, or by shunting equipment from city defences, borders, storage etc.
You want 300,000 recruits to fight? you need people with combat experience leading and training them. Those people do not grow on trees in any army, and we know they've had substantial losses in officer corps. Same goes for pilots; they represent years of training and investment, and there are not that many of them. Even just your average specialists; radar operators, artillery officers, communications officers, drivers, tank commanders. None of these are easy jobs, and even if your released pow can't go back to the front, they can perform a training role. Azov, by contrast, really just have propaganda value.