Any Expandable Launch Vehicle (ELV) even to just Low Earth Orbit (LEO) here will have a prohibited no-fly buffer zone several dozen kilometres in radius around the launch site and a danger designated launch corridor that stretches across the entire South China Sea (SCS) and further more.
You are talking about closing and shutting off the entire Singapore Flight Information Region (SFIR), airspace under the authority and control of Singapore Air Traffic Control Centre (SATCC) to all aviation and maritime traffic. Good Luck with that!