It's a combination of things. One is that he'd been doing it for so long that his movements were less super stiff and formal. The other is that he kept his hands low because he had to avoid takedowns in MMA. Chuck was also a really good wrestler (in the sense that he used it in reverse, having a great awareness of his body to stay on his feet) and won a lot of wrestling tournaments as a youngin, so that may have fed into the lower handed stance.

He has gotten to the point where he has adapted his techniques to a more natural expression. He can afford to let his hands drop because he can do more than block, he can parry, counter, evade. His stance had to take more into account than just striking. In time, we all adapt what we know to suit our own abilities.

Im asking because i just started training in Kenpo and i found out that Chuck Lidell was a 5th degree black belt in American Kenpo or Kempo. So i thought maybe i could get a good visual of some more techniques and form but i am taught to hold my elbows in and my stance is orthodox. He just keeps his hands low and looks sloppy even though he was a great fighter.