Kentucky has penalties for conceal carry in a bar. But they do allow it.
According to the bar owner’s Twitter post (scroll down in the article to see it), the shooting occurred in the bar’s outdoor seating area. Murderer just walked in off of the street and started blasting away.
Personally, the randomness of the crime plus his actions afterward (not fleeing the area, hiding in the bushes nearby, smiling after capture) looks like illegal drugs or some other form of diminished mental capacity.
The Breonna T-shirt is probably just a stray, noncontributory fact.