Full disclosure: I have not been following this outside of my usual addiction to TVC.
Regardless of anything else, this is a perfect example of two things. First, traffic stops are stressful because the cop has complete power in the situation. Even if the cop is wrong, there's no recourse until the driver has been punished- fairly or not.
Which edges into the second issue. With that complete power can come abuse. Or not. Telling the difference is difficult, especially since the benefit of the doubt, legally speaking, is given to the cop.