Old drivers have issues with XWayland. There's nothing fishy about that statement whatsoever. Hell, NVidia only JUST got XWayland working, though that's probably more an issue of corporate stubbornness.
I think NVidia have every incentive to oppose Wayland. The graphics and post-production studio market mostly uses NVidia Quadro cards on linux workstations. They choose NVidia because only NVidia has a fast, stable, minimal-artifact implementation of X11. Being able to code drivers for X11's crazy architecture is actually a competitive advantage.