Here's the doctor that appears in MGS 5, he bares a passing resemblance to Dr. Kio Marv, an old MGS character.
Here's Dr Sergio Canavero, director of the Turin Advanced Neuromodulation Group in Turin and the man behind the first planned human head transplant.
Aaaand here's the English, Japanese-based actor Ian Moore Kojima has stated the doctor is based on.
Here's the content's page for Dr Sergio Canavero's book: Head Transplantation: and the QUEST for IMMORTALITY. People have been reading a lot into some of those headings.
Most people thought this Kojima tweet referred to his alleged departure from Konami. The head transplant theorists have other ideas.
Look, it's just Kojima holding a severed head. It doesn't mean anything.
Dr Sergio Canavero isn't afraid of publicity, as proved by this press shot he posed for. Some people even say the freckle on the head's nose matches the fake head used by Kojima when he appeared in his Joakim Mogren disguise.
That's it. We're done here.