I don't see any problems with preserving one if they can get enough cash together, and convince PN that their intentions are honourable. If people weren't interested in saving certain examples of locomotives and rollingstock, then we probably wouldn't have much stuff in preservation, as it would have been lost to the scrap heap. This sort of thinking should be encouraged if we want to see parts of our ever evolving rail system preserved for future generations to enjoy. Granted, you can't save everything; but there is no harm in trying to preserve some of the more important pieces of our railway history, and I think a second series X certainly warrants that sort of attention.
To those making this proposal, it might be worth considering where you will be able to democile it first, and how much it will cost to get it to an operable condition again (presuming that is your intention) before jumping into the deep end. Test the waters, and come up with a sound plan before you act on anything. There is an awful lot to preserving stuff, especially if you want it to be operational. You will also need a hell of a lot of money, and that always needs to be kept in mind.
Either way, it's your baby. Good luck with it.