Law change
As at October 2024, a Bill has been introduced in to NSW Parliament seeking for a general exemption from wearing helmets for Sikhs riding motorcycles, bicycles and electric scooters. This Bill has not yet passed. You can read the text of the Bill here, the explanatory note here and the second reading speech here.
Relevant links (e.g. Media, Academic Papers, Opinions)
Motorcycle helmet exemption issued to NSW Sikh (date unknown)
State specific Sikh motorcycle helmet laws: