Well, I do suggest you address the issue of Krootox Rider's toughness. If the Krootox is listed as T3 (representing the rider, not the Krootox), then I believe it should be allowed to take the Ork Hybrid adaptation. Why would all the Kroot in a kindred get bigger from eating Orks, except the ones riding about on a Krootox.

It makes sense for Trackers, Prey Shapers, etc. not to get it, as they're already T4 (representing their mounts). But the T3 is the Kroot, and that should be adjusted.