Hi-E did build the "Cosmopolitan" frame that was riveted together. Not sure if that was to avoid welding or just to be able to work with thinner material.

The rims were likely riveted to be able to use sheet stock instead of investing in an extrusion die like most rim manufacturers.

Another factor might be that Harlan Meyer came from the aerospace world, and may have been more familiar with riveting as a construction method.

It's worth checking out the Classic Rendezvous page on Hi-E to get a look at the full range of Hi-E products.

edit: wow... I forgot how old this thread is!

Steve in Peoria