I think you're splitting hairs... Lot's of accepted BDSM artists illustrate tortures and abuses far beyond what is acceptable within the lifestyle, from mutilation to meathook suspensions and decapitations.

No one questions that those are not part of the BDSM art scene... snuff is just one of the many logical endpoints for any story that begins non-consensual... maybe even a few consensual scenes that end with a surprise.