He is not detained in expectation of criminal charges. Hes detained as a "material witness". The Supreme Court of the US allows "material witnesses" to held until they testify. Its not against constitution or any law.
our founding fathers are probably rolling in their graves now
They already spun themselves into dust during Lincoln's presidency. If not FDR and Johnson finished them off.
Never has "original intent" been a part of our legal system. So whatever the "founding fathers" originally intended means nothing. The founding fathers never intended for a federal of the size and scope we have now.
A liberal bringing up original intent is comical any way.
Theres nothing illegal immoral or unconstutional about this guys current treatment. His wife admits he has given money to an organization that funnels money to terrorists. They have confiscated his computer and some financial records. But the fact you dont know why hes held is immaterial. The government is well within its rights and a federal judge has to agree with them.