As a last resort, it should be possible to download and save Microsoft patches and the current Guardian version (which should include the current definitions) on one machine, for transfer and use on another. This capability has been available for IT masters who want to control when the runs happen on machines on their networks and so that they could deploy via "scripts" on a network. I would expect that you could do the same for AV definitions updates from most providers, but haven't looked at how many offer that capability accessibly.
Just another generic thought, in lieu of one that might really be useful. ...