the laws of physics might apply a little bit, but until you're trying to land those 2700s, you really don't need to worry about it. Your body size is proportional to everyone elses. And think about it: why would a lower center of gravity help you spin faster? That's a completely different axis.
Some dude on the TGR forums a couple years ago compiled a list of the current top 100 (approx) male pro skiers' heights and the average height came out to about 5'11" which is slightly taller than the average male (5'10"). In other words, skiing isn't a sport where it is mandatory to be tall to succeed so you get really amazing skiers from all over the height range. Peter O, Liam Downey and TJ Schiller are all pretty good skiers who are tall. And I'm 6'4" and can spin a lot.