Whether you tell someone that you have a gun, draw your gun, or fire your gun you must meet the same criteria. This criteria is the ability, means, and opportunity to cause immediate harm to you or your family. Your goal is always to stop the threat. If you draw your gun and the threat goes away all is well, call the cops and report the threat to you, state that you will file a complaint. I am not suggesting that you wait for this individual (or group)to make up his/her mind. The criteria has already been met to shoot before you pulled your weapon. What I am saying is that in the two seconds that it took for you to pull your weapon they may have rerun their cost/benefit analysis.
As far as being handicapped goes, yes this does affect your right to defend yourself. Nobody is suggesting that a handicapped individual can wander down the street saying "Great someone that is stronger than I, BANG, how many points is that now". What they are trying to say is that takes less ability and less in the way of means to post a credible threat to someone that is disabled. This is called disparity of force. Along a similar line a 5'2" woman may well be able to draw on a 6'2" unarmed man due to disparity of force, if she is threatened by him. There are probably a few married men out there that would argue this point. :)
A handicapped individual might also be less able to retreat. In a video recently posted on another thread we see a young man pick up his pack and run out of the area immediately prior to three individuals coming through the door in the middle of a gun fight. When I was his age I would have done the same thing. Today I can not move that fast. A handicapped individual may well not have the opportunity to retreat that a faster individual would. Had that not been a youth standing there but an armed individual with limited mobility their options would be totally different. I doubt that those two would be interested in any living witnesses.
None of us here is writing a book. All we have space for are a few quick points. Your State, your ability, and your situation will all affect your response.