The internet is a dangerous place, and more abused than used.
Now when it comes to Jeffery, I think he's more of a troll than an actual bad guy. At least judging by what I've seen of him. If he's really a pedophile giving himself away on an open forum like imgflip would be pretty stupid. But as Kate rightly noted, most pedophiles are just pretending to be nice people or even somebody your own age in order to set up a trap.
The power of moderators does not go further than the community/network they moderate. Having moderated many communities myself over the years I had many issues in which people were e-mailed with all kinds of harassment stuff, varying from just trolling to sexual stuff. Although the misery started on the website it went over to e-mail, or MSN (doesn't exist anymore), or Skype or ICQ or whatever networks we had back then. And indeed to even phone calls. And what can a moderator do then? Nothing at all. Bans may normally only be given for misbehavior on the website the moderator in question moderates. As soon as the bullying passes over to another network a moderator is powerless.
I can also say this in the other way around. When I moderated site A, I was sometimes warned about people who did bad stuff on site B, however I wasn't a moderator of site B, and all I could say then is that what happened on site B was at the responsibilities of the moderators there and that I had to keep my mind focused on site A. Since site B wasn't an associate of site A, I wouldn't get any data from them, so no way for me to act. All that could be done was keeping an eye on them and make my own judgment.
When it comes to point 5 in Kate's meme... Yeah, I know all people younger than 18 are gonna hate that. I would, for sure. Now in my case that wouldn't be fair to compare, as we didn't have internet back in my minor years, and the relationship with my parents is.... I better not talk about that. But still, I know it's incredibly nasty when your parents keep an eye on you when you feel you can act on your own. It's part of growing up. And normally I'd say, go on, meet your misery and learn the hard way, but as the damage the internet can cause is permanent and can ruin the rest of your life or worse. A very famous story (because it involves a YouTube video which went viral) is the story of Amanda Todd ( https://en.wikipedia.org/wiki/Suicide_of_Amanda_Todd ), who got herself so deep in misery, thanks to the internet, she eventually committed suicide.