I doubt Singapore could meet its energy needs from solar even if every square centimeter was covered in solar panels.
But the point is, the pumped storage could be elsewhere in SE Asia rather than trying to transfer power from the other side of the planet.
Look, so solution is perfect. It is stupid to say “well that whole idea should be thrown out because it won’t work here.” That’s no different from anti-solar people saying we shouldn’t have solar because of clouds.