I think one of the points Nephi taught us, through his experience in seeking the Brass Plates, killing, and dressing up in Laban’s clothes is that there are the important general rules and we need to rely on the Spirit to apply the general rules to our everyday lives. You might say that Nephi was lying when he dressed in Laban’s clothes and spoke in Laban’s voice, but he was being directed by the Spirit. Perhaps more important, I rarely hear of folks who believe Nephi was in the wrong for killing Laban, as directed by the Spirit (indeed, your posts did not raise a concern with killing). Yet, “thou shalt not kill” is a far more serious commandment than lying or stealing. If Nephi was not guilty of murder, it’s tough for me to see how Nephi could be guilty of lying or stealing the Brass Plates.