Young men drink coffee and read books just outside some buildings on a sunny day; an older bearded man in a dark blue shirt glances at a younger man in a striped shirt, who has a red toy crab on the table next to him.
The older bearded man is indeed Gandalf the Grey.
Young men cannot be an older man.
Just because an old man wears a dark blue shirt does not mean that he is Gandalf the Grey.
The older bearded man cannot be Gandalf the Grey because he is indeed dead.