Hey - good question!!!
Each of the three WLF transfer box shaft is supported at both ends by two bearings (top/bottom are timken tapers, centre shaft rollers/balls). Surprisingly the front axle declutch unit (which is a short shaft with a propshaft flange at one end and a sliding dog clutch at the other end, which mates to its alter ego on the transfer box shaft) is also independent (i.e. the short shaft has two timken tapers and does not rely on the end of one transfer box shaft for total support).
However - the transfer box shaft has a hole in one end, in which sits a spigot of the front axle declutch and drive shaft unit (for additional support when under front axle drive load). Both shafts would normally rotate at a similar speed, and would only rotate relative to each other when the rear axles had lost traction when not in 6 wheel drive, or front axle was turning very tightly).
With no gearing in front axle the plain spigot bearing shaft would rotate continuously against the idle front axle shaft spigot, and could well be liable to seizure in the transfer box shaft, at which point the propshaft would then simply rotate at same speed as if in front wheel drive.
You could always cut the spigot off the declutch shaft, but I don't think it would then be suitable for use in front wheel drive without the benefit of the extra support which the spigot offers.