According to the interview in Democracynow (linked in OP), and according to Congresswoman Rep. Zoe Lofgren, Mr. Ng was in fact, legally residing in the US having married an American citizen, at the time of his detention.

But the argument that being an illegal immigrant (or "alien") by default makes you an Untermensch and subject to inhumane treatments, tells a lot about the person advocating that argument and the government that practices it.

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Déjeme decirle, a riesgo de parecer ridículo, que el revolucionario verdadero está guiado por grandes sentimientos de amor. Es imposible pensar en un revolucionario auténtico sin esta cualidad.

-- Ernesto Rafael Guevara de la Serna