His heart was used to create the touch of malice. He intended this so he could live on inside the weapon.
If he's living inside the weapon, I think he should talk to you when you're using it (a perk on the upgrade tree that you can turn off at will).
A few ideas for what he could say:
1) He could get angry when you kill hive majors or ultras.
2) He could taunt you when you miss a shot.
3) He could respond with complete and utter confusion when you use the ToM against him in Regicide or the raid (you're essentially using him to shoot at himself).
Oryx is by far the best villain thus far, and I want something other than the mask to remember him by.
Do you guys agree?