>>213609501 (OP)A few points..
1. he might not refuse any favor asked by a friend; but Emiro wasn't Vito's friend, had never been, as Vito pointed out.
2. No one got in to see the Don without an appointment. Meanwhile, others were refused appointments on the wedding day because Vito knew the answer was going to be no. But in this case, he allowed the appointment because he knew the answer would be a qualified yes.
Side note... that's also why Vito asked with curious concern why Luca wanted to see him. He didn't want Luca walking in asking for a favor he was unprepared or illsuited to perform. So when Tom tell his that it was just to say thanks, Vito was fine with it. Meanwhile, Luca went out of his way NOT to ask for anything, as a sign of respect to his Don; (aka: being one of the few people not asking him for something that day)