Color rendition is something quite subjective, and depends on many factors. Monitor, exposure, color temperature etc...
When for instance comparing Leica M and Zeiss ZM lenses, I tend to prefer Leica colors, less saturated. Yet, I nevertheless like the Zeiss ZM colors very much...But this can change from lens to lens, some ZM are more, some are less saturated . And it also depends on which software you use, LR or else.
Zeiss EF lenses have -for me- very pleasant colors, but nicer than Canon's EFs? Hard to say.I wouldn't go so far.
I do believe what you wrote, but would I see the same advantage for Zeiss? Possibly, but not certain.
One fact is a certainty: Zeiss produce some of the very best lenses around. But, just like my Leica R lenses, I don't use them wide open, unless for static motives. Lack of AF is for me, a serious drawback.
PS: To be clear, I use only Zeiss ZM and Classic, neither Otus nor Milvus. If I did, my statement could differ.
But maybe, the next Otus will be AF? Then I might very tempted...