When contacted, a Land Transport Authority spokesperson neither confirmed nor denied the legitimacy of the map.
Here was their response:
"The planning of our Rapid Transit System (RTS) lines is a complex undertaking, involving careful analysis of urban planning factors such as land use, population and employment quantum. This is first carried out at the macro level as part of the Concept Plan review, where various government planning agencies are involved to map out the long-term blueprint for Singapore's physical development. This is to ensure that land use and transport are well-integrated. A rail master plan is then developed to serve Singapore's long-term transport demand.
Next, planning feasibility studies are done for RTS lines which are identified for implementation in the near to medium term (such as the RTS lines identified in the Land Transport Master Plan). For each of these RTS lines, rigorous analyses such as travel demand, accessibility, land impacts, and engineering considerations are studied. Inputs are also obtained from other government agencies to determine how the proposed line can reap maximum benefits for the community.
Unauthorised maps often give rise to confusion. We advise the public to refer to our website for official and accurate information on MRT lines."