Not only was it not designed for those environments, what's the point? The parts are aging, machines that old struggle even without the increased stresses of space, and as the station ages, more and more effort has to be spent on maintenance and safety.

The thermal regulation system was designed for 45 minutes in day followed by 45 in night, the communications were designed around being within realtime communications range (eg astronauts remoting into PCs on the ground for personal browsing, so as to reduce risk to the station's own computers) and there are no reasonable crewed or uncrewed vehicles available to maintain the station at that distance. The station is also likely to struggle to deal with docking to either lunar lander, given their size.

We can't turn it into an orbital museum piece without maintaining it, lest it fall apart and cause a massive amount of debris.

We're still early in our spacefaring days, there are still many more historically relevant space stations ahead of us, some of which we may actually have the ability to properly preserve. For the ISS we'll have to settle for the astronaut training models used by NASA.