Like it! I think there is some truth in what you say but I don't buy that it is the main reason for camo. At least not here, where visibility is often poor. I think the aim is to make yourself harder to see, to hide you and, if seen, to disrupt your size & shape so that apparent threat is diminished and unclear. You are right though, many fish are curious. It might be interesting to conduct some experiments to see if what you say is right though e.g. wear something unusual & easily seen but obviously not camoflage, perhaps a bright yellow wetsuit (although I hear sharks like "yummy yellow") or white (although sharks like that too - see portinfers shark-eaten white/red-head kayak picture - and the underside of fish is often white, presumably to act as camoflage against the surface/sky):hmm.
I try to hide when spearing. In a black wetsuit, at the surface or midwater I can be easily seen (black fishing plugs & eels are quite popular here now, as they provide an easy to see silhouette near the surface, esp. at dusk). I probably look like a large ungainly seal - which would be threatening to most fish. So I try to hide as much of me as I can in the weed or behind a rock and that does seem to be much more effective. Sometimes the fish do come into investigate but usually not when I am fully visible.
I am intrigued by the "macro" camo described on the Jersey spearfishing website & used on the Predator wetsuits used by Miles and other SA spearos. It doesn't hide the diver but breaks up their shape & outline. So you have a point. Apparently some continental spearos use unmatched tops & bottoms to achieve a similar affect. I would think wearing a different colour weight vest or a T-shirt over your wetsuit might achieve a similar effect, but perhaps straight lines are bad, perhaps camo/pattern would work better. It might also be better if the fish were more aware of your legs or torso than the firing arm pointing at them. BTW I have an Omer "mimetec" (camo mask) but its not really very camo, the flange is shiney so you can get very distinct straight high-lights on the nose & forehead, & the only camo part is the lens-frame & even that is picked out with a distinct black interior edge; an all matt black mask would probably be better.