This situation doesn't really seem like it's "history" in the same sense, considering it happened so recently, governments are still actively working against them as they attempt repatriation, and the TLD issue is fresh.
But: You can't excuse one wrong with another wrong. The fight about the TLDs might be some little thing, but what happened to those people is an outspoken injustice and I can't comprehend, how modern countries could do such things in the last decades.
The comparison to native Americans is good, because it shows, that the methods are still the same, the deeds are just hidden better nowadays.
Nobody is trying to say that Native Americans didn't get a raw deal; only one person is trying to say that because Native Americans got a raw deal a few hundred years ago, it's OK to do the same to the Chagossians right now. This is the sort of logic people always employ when they're trying to feel better about participating in something shitty. It's the "But he hit me first!" of ethics.