The usability of iPhones and iPads is a great example of how he was right. They're very easy to use and no functionality was hidden in a right click menu: it had to be visible somewhere.
Right click was still always available as a shortcut for advanced users.
When the context menu was introduced, it was initially designed as a shortcut to actions that were already available elsewhere in the UI.
Just because the feature is available somewhere else in the UI doesn't mean that the shortcut for it must be a two-handed one.
But I remember noticing years ago a large room of tech professionals and 100% of the Windows users had mice plugged into their laptops, and zero percent of Mac users did. It was a failure of the Windows ecosystem that people needed those imho.
It's not 'no support', it was an insane default. For all the talk of 'easy to use', there's a reason context menus exist. You can't just cram every context-specific interaction into an omnibar or a leftclick. Non-trivial software is complicated. Adding that friction to its use does nobody any favours.
Yes, in the decades since... Trackpads have gotten a lot better, but at the time Jobs was pushing for that nonsense, they simply weren't good enough. (And didn't exist at all for non-laptop computers.)
Note that in non-trivial or professional software it's typical to have a hand on the keyboard, because not even a second mouse button is enough. Hold 'q' while dragging to adjust exposure in capture one, etc. Or they have dedicated input hardware like mixing consoles. Or they plug in a speciality mouse.