Well, obviously I don't know whether they had children of their own, but at their age, whether they had kids or not, the point was, they likely managed without needing special parking spots.
I'm younger than them, only 62. I had four children under six with no special spots and car seats were absolutely mandatory. I'd get the pram out, put the youngest two in it, then unbuckle the older two and they each held onto one side of the pram. Then, getting back in, oldest two in the car, then I'd load the younger two into the car, fold the pram and pop it in the boot. Totally doable.
Is it nice to have slightly wider spots? Yes. Are you going to be okay without one? Also yes. The same way you would manage if the shops were busy and the spots were full, being used by others with children. You'd just manage or park a bit further away for more space.
You managed to miss the point though. When you decide to escalate a situation, it's a choice. You never know how the other person will react though. The extra comment and the photo meant you found out. Even in my most pissed off state, I'd never take that chance, I'd fume internally, but there are some very unstable people in society, so I wouldn't be risking escalating a situation like that and especially not with a child with me.
In life, you can be right, and it's clear you really want to be right, but it's also important to be safe. In this case, you really did risk your safety and that of your child so you could be right.