Reason isn't always really Ezra's strong suit.Obi-Wan told him that their destinies aren't supposed to intersect. If Ezra told the others that Kenobi was alive, then Kanan would want to find him too, or Rex would, and it'd throw everyone off their intended courses. So I guess he has reason to keep the truth to himself. And Chopper just doesn't care.
I knew it was really Beru. I just have a feeling that "unused take" in this case might mean "Not the stereo version that everyone knows." (I've become a little obsessed with the mono version of the movie in the last couple of years.)