It's not simply just a piss. It's the fact it seems like Goodell is targeting certain players. I'm sure Sherman's perfectly fine with taking another test. It doesn't change the fact that these things are supposed to be random. Goodell feels like he was made to look a fool (he does that on his own), so now he's trying to get him back, so to speak.
Hey I'm all about freedom and personal liberty and I understand that angle. I don't think it applies in this case. If Sherman doesn't want to take the test he's free to renege on his contract, walk away from his paychecks, and get another job.
I've made this argument before but think about the kids man. If some get away with it, eventually most will get away with it to keep up, and eventually the pressure will mount on kids to keep up, most of whom will never see an NFL paycheck. THEY are the real reason why PEDs must be banned. If Sherman is clean, and if he's thinking about the kids, he should be more than happy to volunteer to be tested daily. Like I said, what the big deal? A minor inconvenience for what most of us would consider to be a pretty good gig.