Sorry, I was talking about the scenario when a malware taking over the online computer and trying to sneak itself into a USB disk to steal the private keys on the offline computer.
Anyway what would be the obstacles for creating entire transactions offline?
Along with a write-switch protected USB drive it would be possible to make sure the offline computer is never infected, as the online Armory would only validate and broadcast the transactions supplied to it.When creating a transaction you need to know which unspent outputs to use, so knowledge of the blockchain is necessary.
Well, if you are extremely paranoid, you can avoid using USB sticks: simply print the unsigned-tx file and manually type it into the offline PC. Do the same with the signed-tx file to transfer it to the online PC for broadcasting.