I am not a fan of players choosing to be a PO in high school, especially on their high school team. If you don't think college baseball coaches are looking for athleticism, I would recommend you reach out to a few or do a little more online research. If they are looking at 2 pitchers with one having 2-way experience and demonstrating athleticism and the other being a PO (all else being equal) the 2-way kid will get recruited every time.
IMO, too much is made of being a complete pitcher prior to playing at the next level. If a HS pitcher has the appropriate velo for D1, D2, etc., and can command a FB, coaches will show interest. There is no doubt that my son is playing college baseball, as a PO now, because he demonstrated athleticism. I know this because it was a comment made by several coaches and despite struggling to find the strike zone during 2 IN appearance in front of his current program, his velo was great and he made several athletic plays covering 1B and home. He only threw 2 different pitches his SR year and his pick-off move was ugly to say the least. However, he was in CF almost every inning that he was not pitching. He was not a D1 hitter or CF but good enough to start for our varsity team as JR/SR. And if he was able to comment, guarantee he would tell you his favorite HS experience was hitting walk-off in extra innings to beat our school's biggest baseball rival!
Long story short, stop worrying about the little things in HS. If he thinks his strength is on the bump, then work on safely improving velo and the ability to command 2 pitches. Then let him have fun, play a position and swing a bat as often as he enjoys doing so. Just my 2 cents.