Have I missed something? Why would the ceo of a billion dollar company post some pictures of speaking to a hundred or so students?

Because it's his blog and he can post whatever he likes.

Yes, because he wants to post an update on what he's been upto, which I think it's something positive and cool.

Definition of Blog

Short for Weblog; considered to be an online personal diary/journal that may be updated easily and quickly online.

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