Rest Area 51, yeah, I was surprised when they put that up too, and suspected that since it came not long after the announcements about an animated series of Magical Boy, that the purpose of it was as basically a pilot to test out a concept for an animated series. The marketing for it was a little misleading because the artist was just one of a number of artists who had worked on the Steven Universe spinoff comics, not the series. While not inaccurate to say "The Artist of Steven Universe" when the artist worked on a book titled "Steven Universe", it was a little cheeky. 
It's entirely possible though that having never made content for kids before, or been aimed at kids, and with COPPA being relatively new, that Tapas at the time just weren't aware of how strict the rules are when that comic was launched. At my day job, we went to a whole talk with the creators of Popjam on it, and I was shocked by just how many rules there are when making apps for kids. You can't advertise anything, you can't give the kids any means to post messages or pictures without moderators watching it like a hawk, because if any one kid posts any personal information (like a photo of themselves, their real name, their phone number...) that's a COPPA violation and you might get fined... and then if your platform does have means to collect any information like email, name etc. or post content because it's for adults, and appear to be allowing people to post content that appears designed to "attract kids to the platform", that's also an infraction.
