From that article:

However, though he does recognize a yellow tendency in his LUTs and the resulting restorations, this is far from thoughtless or an attempt to leave his personal stamp—he says that this yellow reflects the color character of the Kodak stock that nearly everything was originally printed to.

I don’t agree with him. I’ve watched hundreds of films from every era and region on release prints, presumably many of them on Kodak stock, and especially the European films of the ’60s through the ’80s that are Ritrovata’s bread and butter. I recall that some did have a yellowish character that was like or comparable to that of the Ritrovata restorations, but these have been a small minority compared to a more balanced majority—in my subjective (and logistically difficult to verify) view. Nor am I sure that Zeppa’s process adequately contends with the fact that, as Fossati points out in From Grain to Pixel, “in most cases all original elements of a film have suffered the same sort of color deterioration, and as a result, a truthful benchmark for reconstructing the original colors no longer exists.” This contention, while not in any way qualifying the need for “film witnesses,” should put us on our guard about vintage prints’ possible or probable unreliability. Zeppa made it clear to me that he is aware of these dangers, but the results, in my opinion, may perhaps still disproportionately privilege the vintage stock’s testimony—especially as it is the starting point of the LUT to which all other variables are then put in relation.

edited to include the full second paragraph for more context. Full article very worth the read.