It's not about justice, it's about designing incentives to prevent future bad behavior.

If you have neither control nor information that is sufficient for betting that the investment won't harm people, don't invest.

I own stocks in several companies, as most people on here probably do. There's nothing wrong about what they're saying, I'm a shareholder. If one of the companies I've invested in commits genocide I don't think it would be unfair for me to be punished in some way beyond the monetary loss of my investment.

Though I agree that monetary punishments to the company are much more effective than jail for some random shareholders. They just need to be large enough.