It's worth remembering that autism is a spectrum. We are at the higher end, many benefits, with limited downsides. Others aren't as lucky.

The argument was also a bypass type. Even if vaccines cause autism, and even if autism is entirely bad, it's still worth getting vaccinated. It cuts a lot of the talking points off at the knee. Even if we assume our opponent's position, it's still not an argument in favour of what they are saying.