Or the AI brother didn't agree with his family, including his sister.

It's absurd, but I have no doubt there are plenty of people who would ask an AI to represent a deceased loved one for them and treat that output as accurate. So they asked AI to represent their dead family member and it (being AI) had a forgiving and humane take that likely wasn't accurate and was more a representation of the baked personality of the AI.

The family, presumably, disagreed with their "loved one's" position, but respected their "loved one's" wishes, at least to the point of presenting it lol

Again, it's easy to assume the sister would just engineer a video of her brother saying whatever she would want him to say, but people are dumb enough to believe AI could accurately represent him. If you thought that was the case, then of course you'd present his position as-is. It's the only moral thing to do lol