Something else occurs to me, too.
I was brought up by older parents, probably a bit more traditionally-minded than others of my generation. I was taught very firmly to respect my elders- we used to be sent round to elderly neighbours' houses to do their gardening, and if we did anything indicating a lack of respect then there was big trouble. (E.g. - I once said I was bored, out loud, when visiting my great aunt's house; I was about 6. I got a walloping!)
If an elderly man had said anything to us, we would have been expected to suck it up. In their day, any member of the community had the right to tell off a child and be listened to. I think nowadays people are so much more defensive and certain of their 'right' not be be spoken to in a way that they don't like that they seem to think it is reasonable to react offensively.
I am so, so saddened that the OP and people like her are unable to teach their children to at least make allowances for the elderly: they are of a different generation, with different values, may possibly have dementia and, in this case, could well be living with chronic pain. Certainly he was unable to remove himself from the situation.
One of the first times I went out after having my baby, and old lady said something horrible to me on the bus. I can be very mouthy, believe me- but I just bit my tongue and got off the bus rather than say anything, even though I privately thought she was a horrible bitch.