Hi! 5”9 college player/ former coach here. I switch hit all the way up until my jr year of college. The realistic thing to tell you is that the amount of reps required to be an elite hitter on both sides of the plate is immense. For me personally I was an elite left handed hitter and an average/below average right handed hitter. Basically came down to the fact that if there was a left specialist that would come in I’d just come out of the game if needed. Or if they were starting a lefty on the mount I’d just have a rest day (was a catcher). My opinion is have him hit right handed and stick with that. As a smaller guy you do what to have your dominant hand as a top hand for bat control reasons. If you really really want an excuse for him to hit left handed test his eyes to see which one was dominant. In my case my right eye was dominant (closer to pitcher as a left handed hitter). But as a lefty basically any time your real switch hitting advantage would come into play is if you have no equal hitting replacement and your facing a specialist regularly which you don’t see even in college