I played for Ward, although it was his hitting approach he did not make all players use this method. If you were successful with an approach other that what he taught, he did not change you. Although I used his approach while there, I ultimately changed my approach in minor league ball, it took me a few years to adjust back too the solid back leg approach most typically taught. Charlie Lowe had a similar approach to Ward so it did have some legs in professional ball. After 7 years of minor league ball I came to see why his approach was difficult with wood and at higher levels; there was too much body drift towards the ball which decreased the amount of time you had. It also reduced hip turn speed; as the body moves in a linear fashion, rotational speed becomes slower. Equate it to figure skaters, when they are spinning real fast, they are not moving around on the ice like the tasmanian devil. I have instructed youth players now for almost 20 years and it is my opinion that the less linear and vertical body movement through the stride and preparation phase before the swing makes for a better, quicker, and more efficient swing.
I would not be worried, your son may flourish with that style in college but if he goes pro, he will have to change. It also takes a special athlete to be successful with the Ward style, that's why you don't see it in HS or lower level collegiate ball. Ward coached many successful MLB players, but I don't think any of them used his mechanical approach.