Why I ditched Gmail for Facebook Messages
facebook.com
facebook.com
In short:
He still uses a regular email-client for his work email. He apparently has it open 24/7. That's where he gets most of his emails or "communications", regardless of whether they're work related or private.
It's like saying that you never drive a car, except for those 800 KM's you do every week travelling to work and back -- oh, and when it's raining outside and you don't want to get wet on your bike.