The thing is, it wasn't their business to care. They had no part in it or knowledge of the people involved but they leapt into avenger mode anyway. And a lot of their responses were way outside of civil interactions.

This is one of the very least appealing changes in Anglophone culture over the past 10 years. The world would be far better off if Twitter made personal attacks, doxxing, etc (except possibly against politicians) a TOS violation that lead to account closure.

The problem is, Twitter would be much worse off. They literally profit from hatred and anger.