Yes, ISS is in a vacuum, which is very good for preservation, however it is also subject to cosmic radiation that we don't have on Earth's surface due to our atmosphere overhead. The cosmic radiation degrades everything, metals, insulation, semiconductors, plastics. Failures will occur without warning and can have catastrophic results. There is no room for taking chances in outer space. No one wants to champion a dead horse that might go on to kill people. Let them decommission it according to the schedule of the people who pay for it. And they will not give or sell it to anyone. Too much liability.