Human rights apply to anyone who is human, and these guys qualify. If you start handing out human rights only to those you think worthy of them, then you have no reason to complain when a Chinese court won't allow an American to defend himself in the way you think he should, or when a Taliban government official decrees that a woman is deserving of death for showing her face in public. Everybody has a different definition of who is "worthy" of rights, so the only sane course is to say that all humans deserve the same basic human rights. As soon as you start deciding who is worthy and who is not, you lose the high moral ground.
To me, those who say these prisioners don't deserve humane treatment are like those who like free speech -- except when that speech bothers them, and then they want to ban it. Free speech means you defend that which you find despicable, or else it has no meaning as a concept. Same thing with human rights. If you can't extend the most basic of human dignities to a human you despise, then it has no meaning and you lose the high moral ground.