If it is a corrosion thing, I suspect the issue is because of the pressurizing that takes place with a pump system like for with a Whisper Lite or whatever, and they dont want any risk of leakage due to the pressure and seals or something.
Not sure, but I read something about the coating in the bottle not being okay with alcohol.
Oh, and again no experience with them, but Trangia makes 1L and .5L bottles for alcohol.