As far as whether you can chop a kill pot or not I am not sure about that one.

But as far as having to kill again after you were involved in a chopped pot, that is common practice. Inconsistant or not....

So even if they let you chop or not, luckily for him it ended up in a chop anyway. Either way he should of been the kill button again.

Again to recap. You dont lose the kill button when you are involved in a chopped pot. Sometimes it sucks but thems the rules.

(Im not saying they suck though as far as the other rules like whether you can chop a kill pot or not)