I understand your thinking and point of view, but I'm with SarasotaBill on this one. His motion is fine (until it isn't).
When my son first started pitching and showed a bit of an aptitude for it, his delivery/arm slot was viewed as odd. People kept trying to get him to change it to a more traditional, higher arm slot (he has a low 3/4 slot and looks like he's throwing the ball from 2B to 1st). However, he kept going back to it and kept having success so they finally let him be and go with it ?.
Basically my point is that while Canterino's delivery looks odd at first, upon closer inspection... it just works. Whether or not he will have long term succes... we shall see, but so far the early results are promising.