Thanks, Félix

Yeah, I have informed Trello about this.

While researching about these I have seen many organizations using Public Trello boards to share useful information (like their future roadmap) and they want them to be listed in search results. So, there are also some good uses of public Trello boards being indexed in search results and blocking search engines to not to list them will hurt many users.

And Trello on their end seems to be doing everything to stop a user from creating a Public Trello Board by mistake. The default visibility settings of a Trello board is set to Private. And even after a user creates a Board the visibility level is always shown at the top of the Board.