Programmers are notoriously nitpicky, and avoid making absolute statements in most cases (wait, I'm doing it too!).

This is because we've been trained to be humble by the machines we work with. Computers expose a lot of our mistakes, and over time they remove any illusion that we can be quickly confident about things.

I would take the qualifiers in his post as an indication of his general disinclination towards making absolute statements, not as a lack of humility.