I would think that if it or any other engine leaks a lot of oil or fuel that the ground would be contaminated and the museum would be responsible for environmental clean up and be liable for substantial damages if the oil leaked into a river or lake. Hopefully one engine wouldn't cause a lot of trouble but a museum with a lot of them could create an expensive problem.
I don't know how big of a facility UP/WP has or had up there and what damage might have been done over the years but they could be held liable for any clean up costs on the property they own and maintain including the land they donated to the museum.