That's normally very true. What we didn't say in the article was that we have some customers whose corporate IT departments haven't upgraded yet and we didn't want to drop them on the wayside :)
I think the latter point of his argument still stands. Presumably you're able to justify the cost of testing for and dealing with IE8 problems because enough of your revenue and conversions come from IE8-bound users. If that's not the case, why would you still support IE8?
You're correct. Large corporations take ages to upgrade.