Except of course, Bistamp isn't 'they'. It's not a government or overly powerful monopoly. It's the opposite. Bitstamp is similarly just as scared and nervous about being unfairly singled out by the government as OP is of them.

The way the law is written, entities like Bitstamp (Not only banks, but other organizations dealing with money like this as well) are legally obliged to take precautions that include REPORTING YOU TO THE GOVERNMENT only based on the SUSPICION you might be doing something wrong. They don't have to prove or know anything conclusive about you. So yes, it feels a bit like "thought crime" but thats the law they are forced to adhere to. Charlie Shrem should have taken a hint himself.