Why is this calibre the minium for sambar in Vic? Who made the decision? Did they consult anybody?

The reason I'm asking this is that the 140gr 6.5 bullet would out penetrate the 130gr .270 bullet. It would out perform the 30/30 which by the rules is legal, so is the 44 mag, and a hole host of calibres that would not perform as well as the mighty 6.5. Can this rule be changed?