I'm not a lawyer, but doesn't he also have the option to comply the order to decrypt, and then ask that the evidence should be supressed because the order contr

I'm not a lawyer, but doesn't he also have the option to comply the order to decrypt, and then ask that the evidence should be supressed because the order contradicted the 5th amendment? That would provide a separate route for the constitutional challenge which would not require him to be in prison in the meantime. (Well, presumably he would be in prison for a child pornography conviction instead, so maybe it's equivalent.)