Yes, Kinder Eggs are banned because of the toy, not the chocolate. However, how did you learn about it? Not because it's posted on signs in the customs area or because it's on the I-94.
What, exactly, is the problem with the toy inside the Kinder Eggs? I've been bringing those home for my kids for years and have never had anyone question it. I have declared I had chocolate and been waved through, but it never entered my head that the toy inside was a problem. I think the last one I brought in was an Easter Egg that had a paper hat, a whistle, a plastic figurine and some stickers....how subversive is that?