I my opinion there is nothing that you could do or possibly should do. There is a difference between public and private places.
My reasons for the above comment:
(1) This may be a phurffy designed to dissuade the developer from continuing with the development.
(2) Is the naturist an owner or a tenant? In any case, the naturist will not be living next door forever i.e. the bricks and mortar of the development will outlast the naturist.
(3) A non naturist neighbour may at any time be replaced by a naturist i.e. you cannot guarantee that you will forever have neighbours of your choosing.
(4) If a buyer does not approve of the view of the naturist then they can install curtains.
(5) Being a naturist in their own back yard is not a criminal offence but if they can be seen by neighbours then the neighbours can complain and request an order from the court that they stop.
(6) There are laws against indecency but the naturist would have to cross the line to be deemed to be have acted indecently.
https://www.austlii.edu.au/au/legis/nsw/consol_act/ca190082/s61n.html
and
https://www.austlii.edu.au/au/legis/nsw/consol_act/soa1988189/s5.html