Elevators are for everyone. Same with the sidewalks. If people go on with their pets or walk down the sidewalk its not their responsibility to cater to you and your dog. If he is aggressive, take the stairs. Stop blocking people from getting in the elevator when you and your dog are riding or getting mad that other people use it or walk by.
Here's a thought, if you want to have a social dog, maybe you should work on your social skills so the pup has a fighting chance.—The other Caesar