Personally, I think it's a good thing when predators self-identify. Cops do it with uniforms and silly hair-hats. Encourage pedophiles to do it with Pedobear. It saves the rest of us a lot of trouble.
Look, it's just a cartoon character, and if someone chooses to display it they probably aren't going to be an actual pedophile. The real danger comes from those who want to avoid any suspicion.
But even if a pedophile has a Pedobear sticker on his car, so what? Teach your kids to stay away from that character, kinda like any other warning symbol. And more importantly, teach your kids to be aware of their surroundings and that it is OK to try to hurt anyone who tries to attack them. And teach them how to do it.