Graeber wrote a whole book on this stuff. Had he not died of COVID, he would likely argue:

1) It's not that the Iroquois had a problem with capital punishment, they had a problem of the offender's tribe carrying out the punishment

2) It's not that the Iroquois had any particular sense of mercy, it's that it was up to the Iroquois to figure out punishment at the time and if they didn't get to make that choice, nobody did

3) It's not that the Iroquois had any real intention of recognizing the European's right to Pennsylvania, it's that the Iroquois had no use for the concept of land ownership

4) It's not that the Europeans bent over backwards to recognize Iroquois practices, it's that they were willing to do anything in order to avoid recognizing Iroquois sovereignty

The Iroquois perspective on the problem was "he's our guy to kill if we want to. If you won't give him to us, you don't get to kill him either." But there ws this whole "noble savage" thing that Europe got wrapped around the wheel on without actually seeing the people in front of them as people.

What "we could learn from the treaty that followed" is "never never extradite ever" because in tradition the world fucking over, if you commit a crime on my soil I get to prosecute for it. Anything less is imperialism.