There's a lot of nonsense being talked here about lack of professionalism. The professions have moved with the times. It wasn't so long ago that it was considered beneath them to advertise their services.
Twitter has become a valuable tool for business. There's nothing wrong with promoting your business in today's world. All the professions now utilise social media. It's not considered unprofessional to use it unless you create a conflict of interest, breach ethics, or disclose confidential information.
I think it's great that Dan Meis engages with the Everton fans, and has a bit of fun with it. It's great that he seems so personally engaged in, and excited by the project, rather than just signing off on a design prepared by someone working under him.
I'd love to know why people say this is unprofessional.