Context. Although...this guy might be so socially out there that context is latin to him. The brony bit is completely whatever. It's a catchy name, that has gained pariah status. Some like that, others don't as much.
Sexualizing the characters, well that's...a different subject. Who is to say that it's right or wrong? Even I wouldn't approach that one. It happens, I kind of have some theories, but humans have been doing this since they've had excess sexual energy and too much time on their hands, so as long as it's not too squicky, why not let it ride?
Showing pony porn though. To me this is like the guy wanted to show his colleague/friend analogue something fucked up that he found amusing and fucked up. Just like millions of other people do on the internet every day. I don't think he was showing it to seek approval. He can't be that out of touch. But he knows that people like laughing at completely wtf shit...so that's why I think he would have shown pony porn.
Now all three of those things could someone who's off, but possibly could be just this guy being cast in a bad light.