Space colonization requires the launch of spaceships from Earth, even if we would use asteroidal resources as much as possible. Humans should be launched from Earth anyway, and at this moment there is no equipment in space which can be used to mine asteroids.
Consequently a space launch facility will be required. The question then where this facility should be located. In our manifesto one can read:
Theoretically those platforms can be everywhere on the planet, even at sea, but is preferable to launch rockets somewhere near the equator. From a practical perspective we should locate our launch site should be at some distance away from populated areas.
Additionally a launch facility should be located in a politically stable country. Further we suggested the Atacama desert in Northern Chile as a suitable location. But as a commenter rightly noticed, one needs to launch spacecraft in eastern direction. In this case this means that spaceships will be launched over Bolivia and Brazil. and problems might arise as these countries might be unwilling to give permission for this.
Alternatively, we could launch spaceships from Northern Queensland (above the 20º southern width). This location is even closer to the equator than Northern Chile, and has the benefit that rockets launched in eastern direction, will fly over sea rather than over land. (For comparison Kennedy Space Center is located at 28º northern width.) Importantly, there is no reason to fear for political instability in Australia.
At this moment we should keep open the choice for a certain location.
See also: Manifesto