From the Washingston Post Article posted:

Initially, before I met him, I did not know what Eric's story was. I knew only from some parents that he was a complete over-the-top preposterous character. Also that he seemed to have cash-flow problems, and that his act had become less tidy over time. For all I knew, going in, he had a substance-abuse problem, or something even darker. Maybe he was doing something bad to kids.

Another quote from the same article:

Why do you think Eric's mom wanted to divulge so much of Eric's personal history, especially the story about the murder of the people across the hall? Eric obviously did not want to talk about it when you brought it up with him. It seems like his mother did not consider whether he wanted this story told. Of course, the article is much more compelling because she told it. Your article implies that the trauma of that incident, combined with the abuse from Rodger, contributes to Eric's absolute dedication to the kids and his own childlike qualities.

Lets not forget one of his friend's opinions:

I ask Eric's friend John Rivers, who is a psychiatric social worker, to clinically diagnose Eric. John paused, giving this some professional thought. "Oh, he's crazy as [expletive]," he concludes, deadpan.

Who knows. But maybe someone who has potential, emotional or past abuse issues, should not be working with kids. Especially when even one of you'r friends think your crazy as shit and is willing to say it to a Washington Post reporter.

And he's fitting the profile of strange performers that get an invite to Comet Ping Pong.