I assume his point is that making stuff that assumes a mouse makes for a bad text-based UI. Absolutely fine if everything is controllable via the keyboard, e.g. if the tabs were labelled F1-Fn and they function keys switched them, or they had an underlined letter and Ctrl+letter switched focus to it, or whatever.

But if this thing requires you to just tab a lot through lots of pointless and rarely used fields to get to a "button" so you can activate it, because it's really all designed to be used with a mouse, then it's a bad text-based UI.

There are some incredibly good text-based UIs around, some going back to mainframe stuff from the 70s. Most of them are optimised for speed of control via keyboard rather than for looking pretty. Almost none of them would be quicker to use with a mouse.