I can't say that this is a theory I ever took very seriously, or cared for all that much, but on reading the OP here: I still don't like the idea, but that is some pack of convincing arguments. I admit that the only two things keeping me from getting on board with it (besides general dislike) aren't very solid: - R+L=J has more hints, and those hints are more prominent. For two main characters to turn out to be secret Targ children seems a tad gimmicky, all the more so in the (highly unlikely) event that Aegon turns out to be the real deal.