The Fascinating TeSi

The answer lies in the fact that types have much more access to their lower process than most typology theories give credit for (and this isn't just a speculation, it can be visually confirmed, so we see a lot of TeSi using Ne heavily, and what it really looks like.) The problem was the functions themselves were never empirically identified up until CT theory, so nobody truly knew how to point them out, nor had a solid based from which to debunk erroneous parts in the theory. But now that we do, we can see where the faults are, and what things were correct all along.

And it just turns out that the "ISTJ" and "ESTJ" profiles don't even exist. As in, they don't describe any real humans, but personas which a small percentage of SiTe/TeSi and some percent of SiFe/FeSi sometimes fit. The profiles were likely made from Isabel Briggs Myers' limited exposure to some people she knew - (who may've been rightly typed, or maybe not) - and then the stereotype was perpetuated forward by other typologists largely as a way to explain to themselves the nature of those people they often clashed with. The people who they weren't truly interested in, and who couldn't possibly be interested in typology. If they were, then well they "couldn't be SJ". Thus the MBTI has been extremely biased against Si types.

High-Si users can use a lot of Ne as well, giving them quite a sense of humor when combined with Te, because high-Si users are actually quite Ne and scattered and curious too, like your dad - but not quite as ditzy as high-Ne users may be. Not sure if you've seen this post but it's my own experience with them.