Either Alice on stack overflow is tying her profile there to her real-world identity, or she shouldn't be signed up for Gravatar. The whole point of Gravatar is to persist a single identity across multiple sites, so I cannot imagine why you would tie a secret or fake identity to a real identity (your email) that you did not want associated with it.

Technically, yes, this article is correct. The Gravatar FAQ even discusses this issue, IIRC. But in practical usage, I can't imagine how this would prove important.