Welcome to April Mikey

Or was it announced even further back...?
No enforcement until the summer after next anyway.
Then if they do give you a ticket, the legal battle will be interesting, no way will it hold up in court
(1) honest but mistaken belief that you were only 400m out.
(2) multiple definitions of shore in various Acts and case law. One refers to 'shore' as land that is dry at any time. So Main Break at Lano has a dry reef for a few days in Nov, thus it is only 20m from "shore". That would also be persuasive if using the argument that the Regs exists to protect water users but is unnecessary. If an incident happens you can swim to the dry reef 20m away (which may be 1m deep on that day but still a lifesaver)
(3) DPI officers estimation of your distance from shore unless he was in a boat and GPS'd your spot