Essentially I argue that a lot of Shiokara's "nasty rep" is due to some very unfriendly English descriptions on menus and product packages. It's hard to imagine a more repulsive name than "fermented squid with the guts".
Shiokara uses the squid's liver only and does not use the rest of its guts. (The squid happens to have a very large liver in proportion to the rest of its body, and it's the liver's contents that makes up half of the Shiokara, the other half being simply sliced squid.)
We had better get used to squid! Squid and jellyfish may be the only seafood left soon, the rate we are over fishing.
The Shiokara might be easier to find than you might otherwise think. If your sushi bar is traditionally-run and has a Japanese chef, then odds are high that he will have Shiokara prepared, if for no other reason than for his own consumption.

Doug