I guess my position is that, even if Gabriel's origins were retconned into the storyline proper after he was created, he's still an official part of the Magic storyline, basically because Wizards says so. Would they design such a card now? No. But Word of God says he's a canon part of the story, so he is. That's how retconning works.
Again, agree to disagree.
Regarding Traft, I'm sad to see he didn't make it into the AVR storyline, but not surprised.