The judge that threw out the indictment explains why he could not legally be detained under the "material witness" law. Please note that the law is called the "material witness" law and one does not just become a "material witness" because the government detains you (illegally) under this law.
I'm asking how come this guy lied.
I suspect we all know why he lied. Deport the anti-american who shouldn't have been here in the first place.