Thanks for building this! I've think about this each time I modify my deployment shell scripts. I kept starting to work on something and just stalled out and went back to the scripts.
Your users are likely well versed in system administration, these analogies don't make anything easier to understand; rather, it serves to distract attention from the core functionality.
edit: I actually think this is an interesting topic. I like the way one usually tries to find a theme that fits the actions the program takes. But it could just as well have been called 'deploy' with 'local', 'remote' and 'setup'. Most administrators would instantly know what is going to happen without having a dictionary lying around.
If you really want to make it dead serious rename 'host' to 'terminal' and 'user' to 'passenger'. And stuff like that.
I even love your name and cmd `fly` :)