To be clear about [1], he isn't being held because he forgot the password to the device, he's claiming he doesn't have to decrypt the device even with a warrant

To be clear about [1], he isn't being held because he forgot the password to the device, he's claiming he doesn't have to decrypt the device even with a warrant. If he claimed he forgot the password, the government would have to prove he really knows the password to keep him in jail. But because he is refusing to respond to the order, he has to stay in jail until either he complies or he can prove in court the government doesn't have the right to demand it. Whether the government can compel you to decrypt a device is still a bit of an open question, with conflicting decisions from appeals courts. It's not nearly as cut-and-dry as you would suppose. The fifth amendment says you can't be made to testify against yourself, but you can, for example, be made to provide documents via subpoena that may prove your guilt.