The ‘colour-blind’ director thing turns out to have been somewhat of a fan myth that took on a life of its own. Or at least a major exaggeration. It’s not a fact and shouldn’t be repeated as such.
Sutherland, the director, was colourblind, however the person making the colour choice was Irv Kaplan.
According to The Official Guide to TAS (by Harvey and Schepis), based on reports of colleagues, Kaplan was “in charge of ink and paint, colouring the various props and characters, and he would do it by himself in his office……It was all Irv Kaplan’s call. He wasn’t listening to anyone else when he picked colors, or anything.”
Irv liked the hot pinks, purples, lime greens etc that were very much in vogue at the time. Other Saturday contemporary morning cartoons (such as Josie and the Pussycats) were using similar palettes.