I have had several attempts to try and sort this with WordPress, but sadly they are deaf to my pleas.
I would like to use my Gravatar, but this is not possible given that it seems that a Gravatar is in fact a WordPress!
I did not know this. With the recent changes, brought in will all the feeling of a draconian edict, I was caught short because I did not know that Gravatars and WordPresses were in fact interchangeable, and to post with a Gravatar means posting with a WordPress.
I think in future that WordPress could be a little more transparent about their intentions. You live in a democracy after all, and whilst WordPress is no democratic organ, it should still live by the rules of a democracy.
In future I will be posting without a Gravatar. I cannot do else.