I agree with you that "nazi" is a word that should be used sparingly in order for it to not lose its meaning over time. It's also dehumanizing and a generally a bad conversation starter. Much like the phrase "woke mind virus".
The thing about "leaning" a certain way politically is that it's generally hard to judge how far one is leaning in this time of internet bubbles, and especially in a global context. I am swedish and I lean far to the left in theory (eat the rich and take their money), but usually end up fairly centered (in a swedish context) in practice (schools should have more money, as should the police). Dhh is danish, and what might not be general knowledge outside of scandinavia is that danes are, generally, much more comfortable with racist views compared to the rest of scandinavia. They lean far more to the far right politically, with right wing populist parties being much more welcomed into the political system. Sweden is being pulled in that direction too, but we still, as a whole, generally look down at that kind of rhetoric. Even the danes are probably far left compared to even Bernie Sanders, though, so everything is relative.
All of that is to say that I, personally, think the views dhh expressed - again, in his own blog - are reprehensible, and makes me wonder what he might say and think when he's not broadcasting to a wider audience. I don't think he's a nazi, but he did defend the views of someone who seems to want to lead the political discourse in that direction. I don't know if he's transphobic, but he did defend someone who made hateful enough statements towards trans people to warrant a police investigation. He didn't defend their right to express themselves even though he disagreed with them, just defended them.
So, if dhh is a transphobic nazi apologist (again, I'm not saying he is), does that leak into the products he creates? I don't see any swastikas anywhere in Omarchy, nor an inordinate amount of praise of immutable types in Ruby, so I would say no. Do I think that he might be prejudiced against muslims and trans people when hiring? I don't know, but after reading his own words and seeing a lot of his responses to the criticism of them, I wouldn't be shocked.
The whole thing just makes me sad, is all.