Along the same line as Epic_bubble,
I personally believe that if a zip file is chosen, the ideal behavior would be as follows:
If there is only one n64 file in the archive, it is loaded immediately.
If there are multiple files, it continues as planned.
I'm guessing this is already part of Paul's plan. If not it is a fairly trivial extension.
EDIT:
After further thought, the ideal behavior IMO would be to specify a rom directory in the options, then simply have a list of roms to launch. This would be more in-line with other emulators as well as android's vision of trying to make the user interact as little as possible with the file system.