Yes, it is admirable they see the misinformed error of their ways but OTOH we all are faced at times with trying to make the best decisions with limited knowledge.
Medical/vaccination horror stories have plenty of chapters on both sides.
I have known a cat that lost it’s leg from a rabies vaccine induced tumor.
I know a young, fit, healthy mother who had a stroke after a “routine” tummy tuck and is now severely disabled.
There are animals that have lost limbs to tumors induced by a type of rabies vaccine and it’s injection location but, I will risk that to avoid a fatal and incurable case of rabies in my animals or myself as I live in a high wildlife zone.
Everything has it’s risk/gain ratio.
I imagine we are biased depending on which side of the fence we have stood on.
If my cat lost his leg to a rabies vaccine I might become more adamant about educating others on this, not uncommon, phenomenon of a particular vaccine and it’s tumor creating outcome.
I think these parents did the best they could for the information they had and now that the information has changed they are open to rethinking their position. That is only a natural and healthy response of relatively emotionally healthy people, more so than a show of responsibility.
They were not irresponsible, they gambled and took a risk, and now they will not repeat the behavior.
I refused to take that Phen Phen weight loss drug about 15 years ago when my doctor wanted to give it to me for being 30–40 lbs overweight.
Turns out I made the better decision considering how many people died from complications from it’s use and here it was being promoted for even fairly modest weight loss. No thanks, I lost the weight walking 3 mile a day for 6 months and lightening up my diet.
Live and learn.
Glad the little boy will be okay.