It wasn't the fact that I couldn't alleviate his sentence because of them needing to own their own justice, it was the fact that my mouth would refuse when he asked me, which he would, he would ask everyone who knew him in this life to help save him from the fire, but that we would all refuse because that's what the script says we will do.
It's not that it's unnaceptable to to the balance, but that we didn't even have a choice in what our mouths would say when we refused.
There is a Hadith that does say we could plead for help from the messenger when we get up to paradise. So in a sense we do may have some free will to ask for mercy.
This hadith was basically to scare the mujahadins from taking more than their allotted share of the booty:
Sahih Muslim 20:4505 - One day the Messenger of Allah stood among us (to deliver a sermon). He talked about the misappropriation of war booty, and declared it to be a serious matter and a grave sin. Then he said: I shouldn't find that any of you should come on the Day of Judgment with a growling camel mounted on his neck, and should appeal to me for help saying: ?
Messenger of Allah, help me.? and I should say: I have no authority to help you; I already communicated to you. I shouldn't find that any of you should come on the Day of Judgment with a bleating ewe mounted on his neck, and he should say to me: ?
Messenger of Allah, help me,? and I should say: I have no authority to help you; I conveyed to you. I shouldn't find that one of you should come on the Day of Judgment with a Person crying loudly mounted on his neck, and he should say to me: ?
Messenger of Allah, help me,? and I should say: I have no authority to help you; I conveyed to you. I shouldn't find that any one of you should come on the Day of Judgment with fluttering clothes wrapped round his neck and he should say to me: ?
Messenger of Allah, help me,? and I should say: I have no authority to help you; I conveyed to you. I shouldn't find that any of you should come on the Day of Judgment with a heap of gold and silver placed on his neck and he should say to me: ?Messenger of Allah, help me.? and I should say: I have no authority to help you; I already conveyed to you the warning from the Almighty.