This isn't like Russia just shut off the lights. The control systems are designed specifically and solely to make it impossible for a third party to steal/activate the weapons, so I think simply assuming that Ukraine could achieve such is unjustified.

And Ukraine's where they're at today because of bad decisions. Russia's negotiations to end the war started on literally day 2. And they involved absolutely no land concessions or anything like that - the big issue was not joining NATO. Such offer would now be labeled a crushing to defeat for Russia, given how the war is going.