I mostly agree, with the exception of the last paragraph. The software world today is built on open source software that is distributed without guarantees and this is an amazing thing. If a liability like that is applied to AI, it would be easily generalized to any piece of software that might be used in malicious ways the author did not intend or predict. It would be akin to punishing a knife manufacturer for a stabbing.
It is ridiculously easy to write a genuinely well intentioned script that encrypts your files and a minor modification can turn that into a ransomware.