You cant ban an archer just because he is running, this is how archers survive and fight...
If they don't shoot then, yes, they can ban him.
No drawing/delaying the round on purpose (i.e. running away or camping unreachable places when you're one of the last people alive)
OK: running away and shooting enemies that are reachable by projectiles
NOT OK: running away or avoiding confrontation when there is nobody to shoot in range or everyone is behind cover.
NOT OK: running away or avoiding confrontation to search for ammo
If you are running/riding away, but not turning to shoot, then you are delaying.
Ofc, in this case the runner actually fought back (he killed the other guy, after all), so it's poll abuse.