Don't you think it could be wrong if you ask people to help you sell the work they did (for free)? What you may see as "derivative work", is just taking the ldraw parts (not done by you), convert it with software (coded by other people), and then sell it for your own profit. You do a 1:1 conversion, not even replacing pattern polygons by textures. This is really cheeky!
After checking what you offer and at which price, i'm really frustrated. Although you sell nothing done by me, i don't spend my free time to produce parts for other people to sell, regardless of whether "converted" or not. Now i really consider not to submit any part or pattern to the community anymore, if that is how it is used... Great! You should make your converted files available for free, like most of the LDraw related stuff.
After checking what you offer and at which price, i'm really frustrated. Although you sell nothing done by me, i don't spend my free time to produce parts for other people to sell, regardless of whether "converted" or not. Now i really consider not to submit any part or pattern to the community anymore, if that is how it is used... Great! You should make your converted files available for free, like most of the LDraw related stuff.