Even in 64bit you're stuck with limits for integer math and string processing and you also have to define your own memory metrics. It's not that you could blindfire data into a black hole and hope that you can find it again if you don't know it's memory address... The warning itself comes from the plug-in, so it stands to reason this is a design feature, rather than a bug. Anyway, parsing a 1GB ASCII/ text file is probably a bit insane in the first place. Even if it would work, the project would be unwieldy to work with and the inital opening would take forever...
And what if you create a custom particle with a dot line/ dot cluster? Also you could try to reduce the mesh to a vertex-only file. This would probably cut its size by 2/3. Try opening it in blender/ Cinema 4D/ Atangeo Balncer and play with the reduction tools. The way I see it, you probably need to streamline your topology a bit ratehr than brute-forcing a huge number of points. Also consider the Pixel Cloud plug-in on AEScripts or Plexus to make your stuff appear more dense...
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