When you join the bitcoin system you agree that spends are permanent and non-refundable. You essentially agree that any spends made from your account in error are all on you. It's like if you go to work for a company that requires a confidentiality agreement and then you go to their competitor and tell them all you know about how the other company does business and they find out about it and sue you. You can't claim 1st Amendment, freedom of speech as a defense because you signed away that right when you took the job and put your name on the confidentiality agreement.
This thread is already too long, but I just gotta respond to that. I think you have that comparison backwards. I know I haven't signed any contract regarding bitcoin. In your example case, the transfer of information to the competitor is irreversible, like bitcoin transactions are irreversible. That employer can't do anything to make the competitor un-know the secrets, so they might try to force them not to take advantage of the information by utilizing laws. Laws that are meant to keep some fairness in society, not to undo things that are impossible to undo. Then your stance would be comparable to "you can't claim NDA, that information was transfered and there's nothing that can be done about it".
Cash changing hands is also permanent and non-fundable, but that doesn't mean that if a huge wad of cash falls into your lap, you can't get in legal trouble if you don't give it back when the rightful owner shows up reasonably soon...