It's really all about 'follow-thru'.
If you 'wolf-whistle' and its a sincere 'icebreaker' or expression of interest, that leads on to eventual 'marriage' - then there is nothing at all wrong and its simply the best, etc.
But if you 'wolf-whistle' with no intention to 'follow thru' and be sincere, but to illicit a hopeful response to her 'putting out' like a easy slut. Then obviously, its going to be penalised when women complain.
So there is no 'black or white'.
You just have to take it for what it is and take it from there.
The law came in because of Construction guys doing the whistling, when in fact they should be 'working'.
Mind you, I remember a renovation on a Kiosk on a beach and females would purposely lay in front of the kiosk and at least 3 bared topless.
Of course, they became quite a 'distraction'.
But if I walked out there and told them to cover up or move away as they were inciting illicit 'wolf whistles' etc.
They would probably have a whinge and go organise a 'slut walk' down the mainstreet