What the hell do you want to 'calculate' here? The map doesn't show natural disasters, sea restrictions, weather patterns, or any of that. You've just stuck pins in a bunch of locations and gone 'we need to consider these.'
What the Singapore-boosters care about is a down-range, on-land site to deposit engine pods, maybe farings, and eventually first stages, but you still have a large body of water to drop stages onto if they break. And we're not sparing fuel or control surfaces for cross-range landings of that stuff. You can't do that in Florida, or Kuru, Vladivostok is too high, and Sydney is suspected enemy territory as well as not having an ideal landing location, and being too far south. It has to be Singapore, or more accurately, one of the islands south of it-Bintang, Lingga, maybe Sebangka. Traffic can be directed north or south around the firing range, hopefully. As for storms-well, we'll have to strengthen the design of the R-5 to handle more transverse winds.