Original meaning is the FBI van shows up and arrests you, I think it’s morphed to a van shows up and puts a black bag over your head, or your app in this case, and your app gets disappeared. I first saw the term on 4chan in like the mid 2000s.
no. parent is sarcastically referring to a (very old now, circa 1990) saturday-night-live skit where the actor always ends up mentioning that he lives "in a van, down by the river"
I think parent poster means that there are no other places to put the app/launcher.
Right I know the van down by the river sketch with Chris Farley, but the parent post is almost definitely using the verb “vanned” to mean the app will get disappeared.
;)