What?

This doesn't make sense.


You could have the weakest passwords of all.. if no one gains access to the file, no one can actually even try a password.
On an airgapped computer, no one is supposed to gain access to the files except for you.
So no password is necessary.

Even on a standard desktop computer you don't need any password if you can guarantee (which you can't btw, but speaking theoretically here) that no one will access it.


What you rather should say is:
"Doesn't matter whether the passphrase is weak if the computer is airgapped"

That statement would be correct.. but would be absolutely unnecessary because no one claimed anything contradictory here.