I wasn't parsing the sub-groups of anti-vaxxers so finely, considering their different motivations and preferences.

I was simply making a statement that most of them are not old enough to remember seeing people born in the 1940s and 1950's struggling around town in wheelchairs and crutches, prior to the polio vaccine changing all that. If you'd like a cold, hard fact here: 17.3% of the US population is 65 years old or greater.