"Just to clarify I'm playing the devil's (not the necrophiliac's) advocate here."
I'll keep that in mind. Still the devil needs a new one lol.
"Dead people aren't really in short supply,"
Nope they're not. Recently deceased are.
It's only a matter of time before the necrophiliac starts contemplating murder in order satisfy his fetish.
"This line of reasoning could be used to prohibit any number of things that are currently allowed. You'd need to show that this particular "dangerous" fetish leads to "deterioration" of society, or at least that they often do. I'm not actually aware of any "dangerous" fetish that has been deemed to do so."
Pedophilia, snuff films etc. There's got a be a limit beyond a simplistic reductionist understanding of "consent".
"Lack of hygiene is a serious (moral) concern?"
Well I dunno about you, but hygiene spreads less infections. If you're reckless with it but still want to live among civilized society you're kind of an asshole.
Granted this alone isn't enough to justify a law against it, it does help when you factor in the other stuff.
"Consent of the family isn't generally required for anything. They can't, afaik, override the deceased person's wishes about organ donation, for example."
That's fine but without any explicit wishes, the family decides.
And there aren't many people out there who would find this acceptable. I also don't know of any person who wants to donate his or her genitals for sex after they die.
"This might be a valid concern but still a pragmatic rather than moral one."
They go hand in hand often and frankly it's not just western culture, virtually no culture would find this acceptable. Not sure how it is moral to trample on people's wishes in their most vulnerable state of mourning a deceased person.
"Oh sorry guys, I know you're mourning and all and want to prepare for the funeral, but we have this guy right here that wants to bone your grandma cause he's an incel LOL, hand over the corpse or we send a SWAT team in"
LOLOL - Again, I know you're playing devil's advocate but lol
This is like WBC on an overdose of steroids.