I have 0 issue with unlockable costume pieces.
My only piece of feedback is that it should be an account-wide unlock once one character gets the badge. You don't need to give the badge to every character, just unlock the Snake capes for everyone. That means all you have to do, if you don't already have a character with the badge, is roll up a villain and spend like 20 minutes fighting Snakes in Mercy and you're done, or send one of your Rogues or Vigilantes or already existing redside characters to do it even faster.