I'm in broad agreement with you, Alito more than likely leaked it himself, which is why no leaker will be found, the justices are above scrutiny. Absent finding another person who we can prove did it, I'll hold on to that idea.
why wouldn't it embolden them to prove the leaker wrong, making the wage of their sin irrelevance? It's just not a strong case. It's as least as likely it leaked from the left to create a political firestorm. We don't know.