The only conclusion that can be drawn from that experiment is "that's what worked for you then."If I were going to try to replicate your experiment, first I'd have to go buy black, black grape & old purple trick worms. I've got over 50 different bags of trick worms (many more counting Netbait and other manufacturers versions of trick worms) but I'm pretty sure I don't have those three colors. I do have many different variations of watermelon & green pumpkin. Plus I fish all those baits on shakey heads, trick worm isn't really a tx rig bait to me, a little too skinny.
Anyway, I remember back in the early to mid 80's, back when the Color-C-Lector was a thing. I had access to one.
It would reliably tell you which color the bass could see, in any given situation. The issue would become, move 5 feet, drop the probe and it very likely would tell you some other color. Move again, same result, maybe the same color, maybe not, but definitely not predictable. Bottom texture, water clarity, clouds, sun and a plethora of other conditions made it difficult to get a predictable result, move and that result could change. When the Color-C-Lector evolved to become the Combo-C-Lector, measuring PH along with light it became even more confusing. PH in a given body of water isn't constant, even relatively close to different sampling points. The guy who conducted the experiments that led to the marketing of the Color-C-Lector was a professor at Oklahoma or Okie State (I forget ) named Loren Hill. Overall the best thing that I got out of the color chooser toy was it motivated me to buy a solid purple/ more lavender than purple, deep diving Bagley crank bait. It caught a few fish before the bottom of some nameless pond re-claimed it and I've never seen that color again.
I think that the only reliable color theory is trial & error, combined with memory, i.e. "What color has worked in the past under similar circumstances". It's part of the charm of bass fishing.
Then, I think we've all seen situations where a color worked for one guy and it wouldn't work for you. I have a bud whose favorite jig color is solid blue with a white trailer. I can't buy a fish using that color. Another instance, a different fishing buddy favors black & blue dingers as his favorite pitching bait (primarily because he goes through many of them and that is a color that is readily available at Walmart. I can tie on a black & blue dinger, same hook, same tungsten weight, same line test, and get out-fished 5 or 6 to one. There is no rational explanation for this ( I'm on the trolling motor and I get first pitch at most targets ). Tie on a different color bait and the catch ratio evens out some. Drawing conclusions from those fishing episodes, to me the most logical explanation is that he's just better at using that bait than I am.