I mean I think the “sole” contributor your are referring to is Keith Packard? Don’t see any reason to not name names here. In any case I guess what I find odd is that while he did a shit ton of work in spearheading a fork, it’s not like it was just him. There were a lot of people, greatly outnumbering the XFree86 steering committee that were unhappy with the direction of the project. It’s not like it was just Keith. That’s what I find odd about your assessment. Obviously there was enough consensus to fork.
You will note that Keith is directly blamed for the fork and undermining XFree86. It sounds like there is also resentment for how XRENDER was done, also driven by Keith, but it would seem with more cooperation within the project. We know that the fork was the victor in history and XFree86 looks unreasonable to most observers but I was merely trying to accurately convey the other side in the dispute, without taking their side.
It does seem like there were a bit of tensions between "Linux on the desktop" types (driven by end user visible features and represented by the fork) and more conservative "old hand at X" types present in the thread, resisting such changes, maybe sometimes for good reasons and sometimes for bad. Though when I google around, it seems Keith and others were active in X before the rise of Linux.
Suffice it to say that Packard was involved in X before XFree86. But the point was that although he was an actual productive contributor he was far from working outside of a consensus. There’s really no sides here. The market could have continued with XFree86, it did not.