In America the term 'Buzzard' is generally used for the species of vulture that are found there. The person who posted the comment saying you had not identified it correctly realised that it was not one of these and then seems to have re-identified it as the most similar species he could find in a North American bird guide. Your comments under the photo do not state that the bird was in Scotland, and
some people seem to assume that everything they find on the internet relates to their own country (and uses the terms they know) unless it clearly states otherwise.
Similar comments were made when the Buzzard/Grey Phalarope story made national press (look at the comments at the bottom after clicking on view all);
Pictured: Twitcher waits two hours for rare bird... only to have it snatched away by a buzzard | Mail Online