Agreed it’s not a switchblade, it differs fundamentally in that it doesn’t have a spring and is not automatic. You take that thing, remove a bit, have this thing.
Wikipedia:
A switchblade is a type of knife with a folding or sliding blade contained in the handle which is opened automatically by a spring when a button, lever, or switch on the handle or bolster is activated. Most switchblade designs incorporate a locking blade, in which the blade is locked against closure when the spring extends the blade to the fully opened position. The blade is unlocked by manually operating a mechanism that unlocks the blade and allows it to be folded and locked in the closed position.
Wikipedia itself contrasts gravity knife with switchblade (as of time of this comment):
A gravity knife is a knife with a blade contained in its handle, and which opens its blade by the force of inertia or gravity. As the gravity knife requires gravity or spinning motion to propel the blade out of the handle, it differs fundamentally from the switchblade, which opens its spring-propelled blade automatically upon the push of a button, switch, or fulcrum lever.
I’d think the distinction should be design intent: the Buck knife and Home Depot knife shown in article photo are not designed to actuate through a spring or gesture. A gravity knife, like a switchblade, is. So certainly closer to a switchblade without a spring rather than a locking blade folding knife.
In Africa we called these knives that were not fully automatic but required a gesture “flick blades”. Some of them are not folding, they slid straight out (or down, gravity assisted) and had a double edge like a dagger. Many of these could become switchblades again if you disassembled them and added a spring.
I also agree with you the enforcement interpretation sounds like they want it to mean any knife you could possibly shake to an open and locked position.