Actually, I heard the real reason the castle is closed is because after the 9-11 attacks they were afriad it would be attacked. And they still are paranoid so they don't let anyone up there. A CM i asked said everything is still intact and everything is just the same as the day before they closed it...Sad really....
It happened around the same timeframe for that to make sense, but I don't think that is the case.
as far as the frank wells thing goes, there is also a tribute in matterhorn. in the iscicle room, theres a crate with climbing gear in it. the crate reads "Wells Expedition". Im pretty sure its the iscicle room.
That website that was linked had something cool if its true in any sense.
"Anaheim - Disneyland - The Disney Gallery - which is above the Pirates of the Caribbean. Workers have reported that after park closing and in the early morning, they see a figure of a tall man walking around in the Gallery. He is believed to be the spirit of Walt himself. Cold spots are also reported by numerous visitors. "