The B&M historical types might want it BUT...,
the unseen issues are moving it off rail, incredible corrosion issues, insurance, and certificate to carry it on the road. Most of this stuff has to go by truck these days. Once you get it onto museum property there's the issue of stabilization, mostly roof and sills, cleaning the vandalized interiors which often contain human waste, drug paraphenalia, all manner of lovely prose spray painted, and more!
In the meanwhile, the museum is working (understaffed) to maintain the current collection.
Most everything i cool and worth keeping if you're a railfan, but the average visitor is generally ignorant of the historic point for saving the item. I hate the argument "You can't save everything", but you can do a few things really well or look like an abandoned auto junkyard. It's just a sad fact we have to contend with as preservationists.