I see no problem in breaking up a beater or discoloured ships and taking off parts that may be perfect to complete a better condition ship.
Is no different to collectors painting and making customs from knackered figures which is widely accepted. Most ships are incredibly common like the figures so no real loss to collectors. It's not like in 10 or 20 or 300 years time, you'll be struggling to find a Millenium Falcon for sale.
It makes you a bit of a dick if your specifically doing it on an industrial scale just for the £££ but unlikely they would be breaking up mint or nice complete ships.
"Anger and intolerance are the enemies of correct understanding."