Ouch... turn the other cheek indeed.
From the avenging actions of the head of the mission, I'm going to guess that they where not the "Not interested? Ok, we'll be on our way." sort of missionaries.
Wonder if the church will apologize for killing their people, torching their villages and attempting to kill their belief systems...
Should they have to apologize? No, the people apologizing didn't do anything wrong, and you can't be held accountable for the actions of your ancestors IMO.
On the other hand the people are different, but the tribe / church / state / etc. often remain. A year from now the US will have a new president, very likely with a different political party. If whoever is running it pulls all troops out of the middle east do you think the Iraqi people would just go "Blank slate, you guys didn't do this, it was your predecessor. " No, the US still remains, even with different people running it. An apology on behalf of a individual is kind of pointless, but one on behalf of the country might help repair wounds.
Same as the church, yes, no one alive today had anything to do with the Inquisition. Most of the people that implemented and ran residential schools are dead as well. But the impact of those actions in peoples minds is still there. In the case of residential schools much more so then the inquisition as there are survivors of that still around. An apology is more a way of saying "We, as a organization, have changed. We regret the actions of our predecessors and agree that they where wrong, we promise not to repeat those actions."
At the end of the day people hold grudges against organizations and countries long after the people that ran them have died. Somewhere along the line someone has to step up and try to mend the wounds, even if they weren't alive when the wound was created. Sometimes even when there side was the ones doing the "right" thing.