People make judgements based on appearance all the time. It's noble to say that if you walk past a man with corn rows, gold teeth, large chains, baggy clothes, tattoos, etc that you would just as soon assume that he's a successful businessman as you would assume that he's a drug dealer, but that is quite bluntly a load of horse ****. Your guard is up, and for good reason. That reaction is built into us to protect us.
Some comedian has a funny bit about seeing a woman in a mini skirt, tiny shirt, really high heels etc, and somehow they get to the point where she says "I am not a *****". His response is "Maybe not, but you're wearing the uniform."
The NFL as a company has the right to set a dress code for their employees. They've already decreed that the hair is part of the uniform. They would seem to be well within their rights to regulate hair length if they chose to, in an attempt to improve the league's image.
I don't think that's a problem they have to worry about though. Alot of guys with the dreds and long hair are really standup guys, like Polamalu and Barber.
This is probably just a lot of nothing.