@nddev@actuallyautistic@AutisticAdam That's a good distinction, I hadn't thought about it that way.
In my musings I came up with another theory, which is that if you don't mean what you say it's because you're not thinking before you talk, whereas if you don't say what you mean you may be lying or intentionally misleading.
Sadly the nt I asked simply laughed and changed the subject, so I'm basically chalking that up to "well if it isn't obvious I'm not going to tell you".