Dan, you apparently didn't see the scope of this post. The title isn't "Dealers shouldn't play", it is "A dealer who shouldn't play". The post then reveals this player's suboptimal strategy. The fact that he is a dealer is not why OnceDear's opinion is that this guy shouldn't play, but is why OnceDear assumes he should be more informed about better playing strategies.
Let me rephrase this: a gambler doesn't make the call (or should have any feelings) as to whether anyone else - dealer or not - should or should not gamble in his life.