So I'm playing aikaido and I'm doing really well, this guy joins and I win and he starts trash talking, I beat him again and now he's angry. Then he ragequits in a huff and says "YEP, TIME TO GET MY BAN ON". Can he ban me for getting a 10 streak? Are the admins gonna come down on me like preying birds? I don't know.

nope, they wont ban you for being good. They actually should ban that guy started trashtalking.

You'll meet people like that often when playing online games. Just grow some skin and learn to ignore them. If you are really offended by a certain incident you can take screenshots and send them to a GM who will issue a warning (Or ban) if necessary.