CAR 166
....(g) after take-off, not alter heading from the take-off heading at a height less than 500 feet above the terrain unless air traffic control directs the alteration or unless the alteration is necessary due to the terrain.
I fail to see how this could be interpreted any other way than ATC can permit you to turn lower than 500'. Sounds like CASA interpretations of law again. One FOI's opinion does not override law.
Interesting observations!
CS