Had you heard the rumours about the cats and his odd behaviour etc. before he was arrested? Or did it come out afterwards. Because a lot of it could have been conjecture after his arrest. Not saying it isn't true. Just trying to get a clearer picture.
He doesn't appear particularly "odd" or "dangerous" in his YouTube videos or in any photograph I've seen of him. I know that's obviously a lot different from interacting with someone in person, but from all media I've saw of him he doesn't seem bizarre. I think a lot of people's perception of him may stem from hindsight and may come from their disgust at the crime he has committed, honestly. You can always look back at things in the past and see them in a certain way, relative to how things have played out in the future. If he hadn't done such an awful thing I feel like people would probably be a bit more dismissive and less inclined to perceive him as such a "strange" person. Could be wrong though.