sorry about delay. Yes, it is a valid scenario, and it should work (and it does for me). If you boot without HDMI plugged in, then of course the kernel won't read the EDID and will use a default resolution. If you plug the HDMI after boot and if Xserver was already started then you will be using the 'wrong' resolution. But if you kill/restart X it should read EDID and start with the right resolution.
If X was not started when you plug the HDMI cable, then you can start it, and it will use the resolution from EDID.
The above applies to the Linux builds, not the Android builds. I am not familiar with the Android builds.
If you see anything different, please let us know.