They're talking about species diversity of vegetative communities. SCL has slower drainage than SL, and there is an edge effect too, likely boosting diversity
I'm of two minds: on one hand, I want to play along with your little collusion comment. On the other hand, I'm a hardcore pedologist, with a decade of field experience.
Shitlord answer: D R A I N THE SWAMP! OVERTHROW THE GUBBERMENT!
Pedologist answer: The finer textures in the streamlets are likely from clays moving with the topography at the short scale, within the catena, via illuviation.
Illuviation… or illuminati??? What does S. Loam know??????
You are clearly an industry insider (pedologist with decade of experience), keep your ear to the soil and let the world know if you hear secrets (silt??) about the Loam crime family (something something big clay doesn’t want you to know something something)
(Hope you enjoy the interest in soils even if it’s from shitlords)