I get the joke and what they're saying, the only thing that slightly rubs me the wrong way about this kind of joke (I'd rather my kid have autism than be dead) is that it still implies there's a chance vaccines could cause autism. When in reality the fact that vaccines have absolutely nothing to do with autism is the single most certain fact we know about autism. Get a vaccine or don't, they're equally likely to get autism or not, shown time and time and time again.

In their anti vax dream world ravaged by polio and measles and many other preventable diseases, kids dying of respiratory failure and encephalitis, or getting life long disabilities, guess what? Exactly as much autism as before. There'd probably be more, since congenital rubella (the r in mmr) back when it was more common was documented as a potential cause of autism in some individuals, and is prevented by vaccines.