He was a jerk. A jerk who was within his rights, but a jerk.
I guess the problem I have is (true at comcast too) the clerk has no power, she didn't make the rules, she didn't write the ticket, she didn't scold the man, she didn't do anything accept take a very low-level job to most likely help take care of her family. Sure, you could say she can find another job, and that may (or may not) be true, but regardless, it's still taking out the aggravations on someone who has zero authority either before or after the fact. She was even nice.
The penny guy has the right to his free speech, just like a neo-nazi has a right to tattoo swastika's on his forehead. Both are dicks, and the first amendment might give them the right to state their opinion, but that doesn't mean their opinions are 1) correct, 2) expressed properly. In this case, penny-man might be right that it's policing for profit, but he should find a way to protest to those who have influence. Go to court, pour the pennies on the mayors lawn, write to every reporter, carry a sign outside the price station.... But don't be mean to someone who has no say.