It is a traitorous act if he does not have a valid reason to kill the inno yes; but in this case he was following the kos placed on miia by Jax; with regards to the false kos, multiple times you see traitors call kos and get people killed, and accidents do happen with kos which is seen multiple times as well; the following round you yourself showed this with lonely dodo being a Traitor placed kos' on people who you then proceeded to kil. The person who was KoSed then can say its a false kos, traitors do this a lot as well, same way with claiming they are proven from killing a T that someone else did.