I think the use of SK to denote a ham who has passed actually came from the use of SK as described in my blog post.

73, Dan KB6NU


On Monday, November 3, 2014 2:09:15 AM UTC-5, Phil Kane wrote:
On Sun, 2 Nov 2014 11:13:05 EST,
(KB6NU via
rec.radio.amateur.moderated Admin) wrote:

SK
End of message. SK is similar to AR, but means that this will be the last
transmission of a contact.

I learned it as AR, reference to SK being reserved as a marker for
Silent Key (deceased). The Morse is the same.

73 de K2ASP - Phil Kane

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon