Amon has actually been in the ghoul world longer than kaneki has and we have no confirmation on what he has been taking part in so to say his involvement is not as profound as kaneki is not actually true.
I don't see Amon fitting so well in ghoul's world. I mean all we know by now about Amon is that he clearly didn't have a tolerant view on ghouls. He could have killed Hina without any doubt, simply because she was a ghoul. He could have lived all his "ghoul life" without trying to make contact with ghouls, and no contact with human either as he felt ashamed about his new condition. Ghouls used to be devil to him. Are they many ghoul who looked as peaceful towards human as Anteiku looked like in TG? I don't think so.
He could very well have just been investigating on CCG, Kanou and all, feeding on ghoul he met, and that's it. That theory does not look that twisted, even if I'd like it to be wrong.