1 - He wasn't British
2 - For a non-British person to be awarded an honorary knighthood or damehood they need to be recommended - afaik, they have to have done something which qualifies as 'making an important contribution to British interests'. Whatever that means. Financial interests? Cultural interests? I have no idea.
3 - Those Americans who have an honorary knighthood / damehood cannot call themselves 'Sir' or 'Dame'. They can use the letters KBE or DBE after their name. That's it.
4 - Queen Elizabeth II was on the throne for 70 years and she only granted 27 honours to Americans, afaik.