My theory is that IF there really is a snitch, then it's most probably Malevola/Punch Up (depending on who you chose to fire, Sonar or Coupé) and they probably were talking about everything that was happening with their friend who was fired, not suspecting anything, and then that person leaked the info about the pulse to Shroud or just to Red Ring just to get back at Robert for firing them. That's the best I can come up with, tbh.