The problem is that they don't have any rights. Google makes the rules for Adsense and you need to follow them. You could try to sue them in court, but do you really want to spend thousands of dollars and waste all kinds of time?
Something similar happened to me with Amazon. They kicked me off, never gave me a real reason, had automated responses, and now just ignore me. They also held $5000 for 3 months. I guess with 100% feedback and no complaints, they need to worry about me scamming them.
You never think that if you are following all the rules that something like this will happen to you, but it will. I now will not base any income off of third-parties.
It might be nice for some secondary income, but the risk is too high that they will destroy your revenue stream.
It's sick that so many people make these companies thousands and thousands of dollars/month and they can't even give them the common courtesy of a real person to talk to when problems like this arise.
The only reason they can get away with it is because they are a de facto monopoly.