You either export the versions and send those or else export the versions as a library and send that. If he will be doing no further editing to the images you could just send the exported versions.
The way Aperture works all the bits in the Aperture library need to be there and hooked up the right way. Attempting to go into the package and pull out bits and pieces will just not work.
Is there any place that I can go to ask for this feature to be thought about? It seems that there is several photographers out there that are using Aperture and would like to be able to make changes to a file on the go (MBP), and have it update the original file as well on their home computer (iMac).
You can ask see Aperture->Provide Aperture Feedback and you're right many folks would like the ability to keep multiple libraries in sync but to be honest I wouldn't hold my breath.
Aperture was designed as a single user, single seat application. At best the intended use was one photographer with a setup on a desktop at home (or in the studio) and another copy of the application on a laptop for field work. When the photographer got back she would export the field work from the laptop and import it into the library on the desktop for further work. There is small ability to deal with duplicates in the two libraries but that is it.
But asking never hurt
With some thought a workflow that cuts down on the amount of data you have to share might be thought of.