I don't think they're actually describing this as a brawl, it's the players running in that they're trying to stop, to try to stop escalation into brawls which have been getting out of hand in park footy. As I said, it is a fairly strict interpretation, and I don't really have a problem with it, if it's consistent. Run in, get banned for a week, tough luck.
If blokes want to punch on, they can always join a boxing or MMA gym with blokes who can fight and will be happy to accommodate them.
PS. That's not to say I'm sure this will work; IDK how much modelling, planning, and testing the NSWRL have done on this policy. It may have the opposite effect, ie. "Well, we've run in; we may as well go for it because we're not playing next week now anyway".