The linked XKCD's are #225 "Open Source" and #239 "Blagofaire" (the one with Cory Doctorow in a hot-air-balloon). Stallman-with-a-katana also shows up in the five-part arc #341-345 "1337". (I don't know if there were others?)
I'm inferring the real-life katana was a joke based on #225 (and maybe Randall Munroe wrote it in again in reference to the real-life object).
Elite collection
Selling off foundational relics to private bidders is imho a sign that an organization is done.