Honestly, it depends on what that property is and if the person went on a killing spree based on their views on property X or for other reasons.

If Property X is something like the color of their skin, their sexuality, their gender, etc, then I would support cloudflare banning them.

I am certainly not the master of what should and should not be on the internet, and neither should cloudflare. As a society, though, there are some things that most can agree on.