It will never be enforced?
OK, this is in QLD but will be probably next as they are actively seeking national conformity.
One large swell a few years back at the Alley the water police sat in the carpark at the boat ramp and fined Ski rider that returned. Many got fines for: Riding too close to surfers/swimmers, going too fast, but mostly no PFD's on surfers getting towed or having a spotter riding backwards on the ski watching the person getting towed (also with PFD and driver with PFD) They sat in the tower above the break and recorded every violation.
Friends of mine got slammed with them all. A costly days surfing. Yes, like riding a bike with no helmet you will get away with it most times....... BUT do not complain when you get fined if you simply choose to do nothing. Like all new laws they do at times have hot and cold periods of enforcing recreational users.
As a competitive body though, users who do not follow the law are not insured. This is a bigger issue than just SUP, it's competitive water sports across the board!