Originally posted by monochrome I got hammered yesterday for saying Pentax would be irresponsible to allow this. The reference was Nikon 9mm - 11mm lenses and Voigtlander extreme wides for Nikon F mount.
I'll try to dig up the post to link it [EDIT:] Here. ("I guess it was just pretty damned irresponsible by Voigtländer to create the 12mm f5.6 and the 15mm f4.5 for Nikon f-mount then. Not to mention Nikon with their own 6mm, 7.5mm, 8mm and 10mm fisheye lenses..")
I still think it would be irresponsible to market a lens that could damage a mirror box - unless they alter the flange somehow (one "ear" is longer and the K-01 mount is accordingly altered) to physically prevent mounting the lens on other bodies.
I didn't read the posts that "hammered" you, but I hope they weren't too abusive. Nonetheless, I do wonder how far manufacturers should go to protect people from themselves. Unhappily, courts often think about these things differently, so I imagine advertising, packaging and labeling will carry warnings, as should the lenses themselves, but there will be some incautious naive who will most likely test the system, at some stage.
Come to think of it, you could probably say the same about the Rear Converter Ls as well, as they clearly have a protruding element, and shouldn't be fitted to lenses that don't have a recessed rear element, but I don't know if anyone's damaged something in attempting to do so. However, the odds of someone trying this are probably less than trying to fit an XS lens to a DSLR, but both are fairly remote, in my view.