Spot on. Brownpants would be even more appropriate.
Actually, I was wrong. The fore-runner to the Hitler Youth was started as a sub-division of the SA just a year after the Sturmabteiling was founded. I didn’t see any reports that they were used to break up political meetings of the opposition, though. But you can’t go wrong in calling them Brownshirts or Purpleshirts, whatever they’re wearing this season.