Ignoring ed, vi is the only sane editor that you can depend on to be installed on every system you work with. Even if you know emacs, it's common to at least be familior with enough vi basics to fix a broken system (hjkl, i, :q, :w)
The original interview was claimed to be for a developer position. If you're a developer in most companies, you never have to handle a random broken system, as usually any and all deployment or production maintenance is separated. DevOps is still an exception, not the rule.
You manage your workstation and your dev/test environments or VMs at most - they have the exact editor setup you like. The only interaction between your computers and "foreign" systems is the code version control system. Your editor, no matter how rare or exotic, is guaranteed to be installed on every system you work with - if you work on your systems, not manage systems of other people.
Even the OS doesn't need to match. You can easily code for Linux deployments on a MacOS or Win machine, and never touch any Linux computers. Heck, you even can code for Windows deployments on Linux machines, though sometimes testing that may be a mess and requires a VM - but you certainly can do that.
