It seems more and more the case that NSP's existence is to give the illusion of electoral contest but without posing an actual danger to the PAP.
On a historical note, NSP was formed in the wake of the 1987 "Marxist" detentions (Ops Spectrum), at a time when the climate of political fear in SG was very high. Either they are truly brave souls who wanted to make a stand, or they were organized by some hidden forces to make sure opposition in SG does not go completely under.
Now it seems the latter explanation is more likely.
NSP looks and behaves more and more like a mole party.