Ugadalou, footwork indeed is very important. But, footwork is something you need to develop off the court. At his stage, or any beginner stage, if you will be concerned with where to place your feet, you will rob yourself of time and slow down the development process.
Your head should be free and your concentration should be on the incoming ball. Let your body position itself naturally.
There are ways to improve footwork with various exercise that don't include hitting the ball. I would recommend these to him at this time. I would also recommend core strengthening routine.
You need to learn to walk before you learn the "dance moves". What you suggesting is equivalent of taking a 1-2 year old child and attempting to teach him a rather complicated dance.
Not saying you should not pay attention (as a coach) to his feet, but you certainly should not suggest he should worry about them, or it is an issue, or "make sure you place your feet like so". Whats needed are subtle little correction that mean very little to the player, but accomplish the overall agenda. For example, I would explain him the difference of open stance VS close stance (off the court) then simply ask him to stay straight and rotate his shoulder, rather then stand side ways. Nothing about the feet. He has been walking, running, jumping and balancing himself since 2 years old. I am sure he can manage to get to the ball and hit it.
My opinion: Run away from any coach that places too much attention to beginners feet while feeding the balls. He is clueless and will clog the players mind with doubt, that will hunt him for a while and limit development.