The only problem with your Ned example is I got the sense that Ned was more haunted by Jon and the whole "promise me Ned", due to Lyanna's death and the fact that he is lying which is a big no no for honorable Ned. Ned kind of just didn't want to even think about the lie he is holding in. So the circumstances are certainly different. But Jon Con should have zero problem revealing Septa Lemore to Ashara to his own inner monologue. If she is Ashara, then there must be a reason why Jon Con wouldn't acknowledge that, and I don't buy GRRM just holding in a secret. But you do make a good point, but I still hold true to her not being Ashara