I have a question, since Robb actually legitimized Jon and named him his heir for Winterfell and the North before the Red Wedding (granted no one knows about this and is still alive or free, the Greatjon knows as does Edmure, but Idont see them getting out of the Twins any time soon and Catelyn would probably die before telling anyone) does this make Jon's rejection of Stannis' offer moot?
Edmure and the Greatjon are prisoners, true... but you are forgetting the envoys that Robb sent to Howland Reed... Galbart Glover, Maege Mormont, Jason Mallister... they are all alive and free.
As to what is and is not moot... the key point is, only a =king= can legitimize a bastard......