When you don't know the difference between a protocol and a markup language I don't you should be in charge of writing tech PR.
Is XMPP a protocol? Yeah, it specifies a machine-machine communication system but it also specifies the structure and formatting of the messages it sends.
Where do you draw the line? If it were a technical discussion, you'd be right that HTML isn't a "protocol". From TFA, I got the sense that they didn't mean a network protocol but something more like a "standard" (without the nasty connotations of that term).
Edit: oh, screw me, the article actually says 'HTML'. I didn't register that and saw 'HTTP'. I'm guessing the author meant that: didn't you ever write HTML when you meant HTTP and didn't catch it until the third reading?
Edit2: interestingly enough, the above said 'ISO' instead of 'OSI'...