By what measure is a (hu)man?: On mutants and vampires...

[WalrusJones]

However since player zombies have been brought up, they'd fall under the same category as Vampires which are considered dead, they're still thinking beings, although possibly not capable of feeling any sensation, and a thinking being is capable of being 'harmed'.

One time I got turned into a zombie, presumably by an admin, and continued to do my chemistry experimentation right next a non-zombie, communicating with him through use of a hand labeller; still sentient, just disabled in some ways.

This raises an important point: Just because you CAN harm it does not make it good.