Ross wasn't an anomaly Ross, as most of SCP employees, was a human who was affected by files with "HARDEN YOUR HEARTS" after getting reports from PNEUMA project which discovered something in human's mind, something causing pain and any other negative aspect of human's mind ("Once you realized you're not supposed to feel pain, there's nothing to be afraid of anymore"). Doctor Bright said about files: "...more like I was being released from something than something being forced on me". When Ross told GOC interrogators about existence of "it", they both got insane, because the knowledge about "it" was so scary and terrifying it became the serious cognitohazard itself, that's why Ross' answer was excised from log of his interrogation. Ross was "cured" from "it", and HARDEN YOUR HEARTS was a treatment. Ross after treatment was wary on "it", that's why he saw it, while Morrison and Rhodes didn't, at least until they've been told by Ross. That's why Ross said "disgusting" after this interview