The folks at adafruit probably do know, but it does make sense if you expand the words: "Control, Alter, and Delete"
That's bullshit (IMO) and the post author (Phillip Torrone - I believe that's one of the owners of Adafruit) is obviously ignorant in this regard.
That said, what he's actually talking about in the post makes a lot of sense. That is the important part.
That's more charitable. Alt is still short for Alternate though, not Alter.