>You know Mark Taylors story about being chemically drugged up and locked away?
You must be talking about a different Mark Taylor than the one I know of.
It was a general reference to use of stenago in that Sarah Silverstein pic. The particular image was defiantly NOT done with PixelKnot. PK is a toy stegano program and leaves a distinctive file structure, which was the pic was lacking.
So I read it as a suggestion that whoever posted it used some serious spook-grade stuff, which the NSA would be able to detect, to send a message to Q & Co. But this program is unfamiliar to the public; so Q dropped the mention of PK instead. We never came within a light-year of cracking it.