I think there are legitimate reasons to struggle with things like capital letters, and you've named a few: non-native language and interface device limitations. There's other accessibility reasons too, like I have some dyslexic family members who use less capitalisation than most. Also, direct or casual communication with individuals, the impact of the extra cognitive load is minimal - 1 or 2 people - so again, no real issue.
The problem I have with this piece is that it's clearly meant to be an intellectual or academic-adjacent piece, and it's clearly meant to be public/read by many people - that's why we're reading it on Hackernews. The author is not putting in the extra few seconds required to fix the problem when writing, and as a result, many thousands of people lose a few seconds each when reading. I feel there must be a point where the cost of the extra reading time to humanity outweighs the benefits of the intellectual contribution - I can't really tell because even if I overlook the capitalisation, I'm not smart enough to understand it anyway.