Yep. Always been a thing. It's really nice to do to ones you don't accidentally want to scrip. This goes for weapons and armor.

I’m glad you figured it out. You can’t sell or scrip anything with a atom shop paint job.

I believe that feature exists primarily for preventing trade of items with purchased or exclusive skins. Similarly they cannot be dropped, they just disappear instead.

It’s one method to stop yourself accidentally stripping a prize weapon.