Do you think using capitals at the beginning of a sentence aids comprehension?
I view punctuation and spelling rules as a way to maximize comprehension (akin to having a linting standard). In non formal writing, I don't see any harm in avoiding capitalization (at least it doesn't seem to me to help understanding / reading speed, etc at all).
One would expect Altman to know how to use the SHIFT key when running a massive business, but, hey - once you achieve escape velocity from society, you don't have to live by its norms or grammar rules.
I can assure you that it would cost most people people here a promotion or a raise if they did this at work.
Then, I guess, he decided, he was too important to follow grammar rules.