> was that autistic people can't tell bad ideas from good ideas
They can tell that. Sometimes maybe even better than others.
What they can't do well is navigate across social clues that others pick up instinctively. That aren't explicitly spoken.
It's not about considering them harmful or not, it's not whether they should be forgiven or not. It's about understanding. An autistic person behaves in a way that you interpret as "being an asshole" not because they can't tell whether they're being an asshole - it's because they think in a different way and their reasoning makes perfect sense for them and doesn't make them seem like an asshole. You lack that reasoning, so you misinterpret their intentions.
The point is to understand why someone may act in the way they do, instead of assuming that they would act in the same way you would.
For instance, something that you would say just out of politeness can be interpreted by an autistic person very literally. When you ask "would you like to make me a tea?", expect "no" to be a totally polite and honest answer. That's literally what you asked about.