Right, but the makers of the murder weapon aren't culpable.

Or do you think a Microsoft exec should go to jail every time someone uses it to write a death threat?

The hypothetical imagined hiring an intern to do a crime and supposed that this might make liability harder to determine. It doesn't!

An intern is a human, unlike Microsoft Word or an LLM, which are tools/machines/etc.

Automated DDOS-for-hire services are not legal either. They're tools/machines/etc, possibly running more or less autonomously.

https://www.justice.gov/usao-ak/pr/federal-prosecutors-alask...

I think we all know it's illegal to sell illegal services.