Hello AHarvey
 
Thanks for restoring the original cycling trail called Roman Trail. It is certainly not "unsunctione trail". According to old and current Royal National Park maps, this trail is published by Royal NP as management trail, marked on its official maps with black dashed diagramatic line. Furthermore, the map legend describes it as allowed for cycling and hiking.
Should you require scanned, photographic copies of such maps, I'd be happy to forward them. Best regards,  Roman Mark Juskey, Sydney Australia 