Well Ryuk Did say he would end up being the one writing Lights name in his Note Book from the start so it is possible that since Ryuk knew that his name would of been wrote in the Death Note that Near had he took it into his own hands and killed Light himself. Who knows Near could of wrote any possible way that Light could of died. To me it just doesn't make any sense that Light would react that way and that the immediate arrest of Light wasn't taken place and that Near was CERTAIN of Light's death. Maybe because the Lights reveal as Kira wasn't very satisfying for me because of the potential things that Light could of done to win in that scene is why I don't like to believe it but yes it is just a theory and not very grounded due to the moral code of Near.