"This way the paper wallet has never touched a computer or a network, and as soon as you eject the device the private key is wiped from memory"

This is not true.  Anyone printing paper wallet should be careful of what printer they are using.  Larger industrial printers have hard drives that record all spooled print data in some cases, especially older models.  Most of them are also connected to the internet.  Some of the newer models have data security or drive encryption installed by default but not all.  Smaller personal and desktop printers that don't have hard drives may be ok.  IMO dedicated hardware wallets are the better option.

http://www.cbsnews.com/news/digital-photocopiers-loaded-with-secrets/