Crush, you're forgetting the role that poor trim plays in silting.
I don't teach non-silting kicks in OW courses as such. I may teach a frog kick to a student who persists in bicycle kicking, but generally most divers slip straight into flutter kicks as a carry over from their normal surface swimming style (most people swim freestyle/crawl). In addition, most new divers are way above the bottom, partly because they are not used to the magnification effect of water and think they're a lot closer, but also because they don't want to crash into things. But even if they're pretty far above the reef with their upper bodies, if they are out of trim with legs dangling down and flap their feet in flutter kicks, they'll silt the place up! So I don't worry too much about non-silting kicks in OW courses--I focus much more on non-silting trim! Even a non-silting frog kick will lift sediment from the sea floor if the diver is leg down rather than horizontal in the water.