Yeah this is just a way to push censorship and more surveillance. Its no secret that Singapore has some Chinese influence and its entirely possible this is just a precursor to locked down devices to prevent the use of encrypted messaging.
(I don't have actual evidence to support this claim so take it how you please)
the play store has geo-blocking apps as a feature. Meaning that, if it was necessary, google could restrict the Signal app from being installed in Singapore, at the Chinese government's request