Actually the tooling is owned and possessed by the USGov, not LM. And restarting the production line isn't as simple as flipping a switch. You'd need all the components made by subcontractors (that are out of business). And you'd also need to find assembly workers familiar with the processes involved in fabricating the airframes etc. Plus the technology is OLD. The avionics are old, 1980/1990 designed systems. So you'd naturally want to upgrade it to the latest standards, which would cost more money and extend the time required to deliver a plane to the AF.
Lockheed Martin have all the manufacturing equipment in storage and have been trying to sell the Pentagon and others on the idea of restarting the production line to build more F22s with upgraded avionics/electronics taken from the F35. To offset the cost of restarting production they propose allowing Japan to buy them too since Japan has been keen on buying them for a long time.