Courtesy of Space
A reactive dog can be rehabilitated but it needs time.
During the rehabilitation process at some point the dog would have to be in public setting being introduced to stimuli in a controlled manner.
As considerate dog owners, we should give these dogs the space they need to help them get over their problem asap.
By allowing your dog to rush toward such a dog despite the warning and pleading from the owner you can greatly stress the dog and set the training back by many weeks or months.
Many owners of reactive dogs have to spend a lot of time to manage the situations their dogs will be in during the rehabilitation process. All they are really asking is that you give them some space. They are not asking you to do the impossible; they are not asking you to give up your dog's happiness; they are not asking you go out of your way or bend your back backward--just leave them alone and carry on, that is all.
When you see a person in a wheelchair trying to get into an elevator, will you hold the door and may be take the next car to give this person the space he needs? When you see that a baby in a stroller is trying to sleep will you not refrain from talking loudly next to her?
That is all a reactive dog owner is asking from you--the courtesy of personal space.