That's an iffy question and depends on the writer who could conceivably write it either way. I always believed that Captain Marvels (will NEVER call him "Shazam") lightening was just the conduit for his magical powers and not the source which exists somewhere else.
So I doubt Thor could control the Shazam powerset but it would be conceivable that Thor could control the transportation device to some extent since the magical lightening has either missed Billy or deliberately been avoided to be used as an attack so it's not like Darkseids's Omega Beams.
I don't think Thor could automatically one-shot BA with a lightening bolt but that would only be due to the whole Marvel/Black Adam powerset and their higher then average defense against magical attacks. It would hurt but most likely not KO him, now if it was Thor using say his Anti-force blast (which technically he still has) that I believe could KO Black Adam.
That Lighting of Billy and BA is that of Zeus, so would have to be Odin Force empowered thor to have a chance to redirect it, not normal Thor!