"Treason against the United States, shall consist only in levying war against them, or in adhering to their enemies, giving them aid and comfort. No person shall be convicted of treason unless on the testimony of two witnesses to the same overt act, or on confession in open court."
Those alleged of Treason must be convicted in a court of law, for that is what the word "convicted" means in America; the Congress has no authority to convict someone of a crime, and neither does the executive branch. This authority lies solely with the Judiciary. As far as I'm concerned, the NDAA contains portions that would deem it a Bill of Attainder, thus violating Article 1, Section 9, which says no bills of attainder shall be passed by Congress.
The NDAA and the US Constitution: Part 1
The NDAA and the Constitution: Part 2
The NDAA and the Constitution: Part 3