The legal precedent is that encryption is a munition in the United States, and therefore protected by the Second Amendment.
Don't confuse people here, there is no such precedent.
Bitcoin is a digital currency. It's not a weapon, it's not a free speech mechanism. There's absolutely no way that any court would deem that Bitcoin is protected within the First or the Second amendment. If the US government has a precedent of seizing gold, why would it recognize the right to own Bitcoin as a part of the Constitution?