Personally, I found his babbling rant highly coherent. That's just his style. He's a really smart guy and a good investor.
I think this came in vogue among the tech affluent during the era of Crackberry supremacy -- easier to just thumb in all lowercase, and a significant portion of communication done from that device made staccato lowercase brevity socially acceptable.
the quick brown fox...
would turn into
The quick brown fox...
which would not translate to the PC. It would just stay lowercase.
It's not a matter of bad habit, it's a conscious choice. When I'm IM'ing with friends, I typically type all lowercase (but with good spelling and punctuation) because it's what they do and it seems less formal. When I'm typing an email or an HN comment, the capitalization just happens.
... I miss my blackberry.
I was referring to the style of all lowercase, and to when I started noticing business people stop using initial caps. I used to catch myself doing it too after using a Sidekick and Moto Q for email on the go; still happens sometimes.