You’re skipping over important parts of the storyline:
“Miles hitched a ride from Miller to the "Strip" area in Tuscaloosa to go to a nightclub on Jan. 15, the night Harris was fatally shot. Miles, according to Miller's attorney Jim Standridge,
brought his gun and left it -- concealed -- in the back seat of Miller's car. Miller's attorney alleges his client never saw or handled the gun.
According to AL.com, police believe Miller left to go eat because the line at a Strip restaurant was long. Around midnight, Miles asked for Miller to pick him up. Roughly an hour later, Miller left to go pick up Miles. It was around this time Miles texted Miller and asked that he bring his gun to where he was, according to police testimony. Miller then arrived to Miles' and Davis' location with the gun allegedly in his possession. It's unclear if Miller drove to the scene at the request of Miles or if the timing was merely coincidental.”
Any culpability on Miller’s part would depend on him knowing Miles was asking him to bring the gun back to Miles so that he could use it in the murder. If, as it appears Miller’s statement is, Miles put the gun in the backseat without telling Miller he was doing so, and if the first text simply asked him to come pick Miles up, there’s no problem there. Miller says he was already on his way to get Miles when the second text asking him to bring the gun came in. If all of that is true, then he wasn’t legally doing anything wrong. The police seem to believe the story so far since he hasn’t been charged with anything.