It's not okay. That very well might be one reason the Meyers family lied. Everyone involved can go to jail if her death occurred as a result of an illegal activity. That mean her son and daughter could be charged if the DA were inclined to press charges. If they were involved in illegal activity, they're all guilty of her murder, even her. Of course, he's not going to do that, but the Meyers family had no had no idea how the police and DA would view this at the time they told their stories.
Remember, nobody has admitted to a drug deal and the DA isn't acknowledging it so it's irrelevant that a drug deal was going down at the time of the shooting. If they all hide a drug deal was occurring, it's fair game who claims self defense. If they admit to a drug deal, they all risk being charged if the DA wanted to.