I don't know if I would call those build instructions supported. I don't have all day just to try out a new text editor...
Then sit down and wait for a download.
They don't have official builds yet. If you care enough you can build it. They'll get official builds probably soon enough. I don't know what you're complaining about..
I think it really speaks to the crowd they are courting with atom and I don't think it's the right way to go. The traction they are looking for will never happen if they have a darling platform.