The question before the supreme court was not whether indefinite detention was a violation of the eighth amendment due to the fact that the punishment is grossly disproportionate to the crime. I believe that life in prison for looking at pictures would definitely qualify as disproportionate and I am strongly opposed to any decision finding otherwise.

The question was also not about whether such detentions are in violation of the due process clauses of the constitution (articles 5 and 14) due to their lack of an appeals process or their confinement of individuals without litigation, a jury, etc. Such an argument would also be one which I would strongly favor.

The question that was before the justices was a states rights issue. It was a question of whether congress had overstepped its bounds by creating a law that allowed the federal government to imprison people for crimes not of an interstate nature and typically beyond federal jurisdiction. The argument the justices had to consider was whether the constitution allows the federal government authority over such issues or whether it is solely the responsibility of the states. That argument is far more complex than the other two arguments and the answer to that question relies on your opinion on the fundamental role of the federal government and the limits placed upon it by the constitution. I tend to be more of a federalist when it comes to my beliefs on the role of the federal government, but since SCOTUS decisions should be about interpreting what the constitution actually says and not what you wish it said, I could see going either way if I had to make such decision myself.

The point I am making is that just because this ruling has consequences that I loathe does not mean it is a bad ruling. The constitutionality of indefinite detention has not been resolved yet. Only one of the arguments against it has been resolved and it is an argument that would have only affected the federal law and would have had no effect on state laws that do the same thing. Even if the federal law had been found unconstitutional, state laws that do the same thing would continue to exist.

A good source for finding more details on this issue is the scotus wiki. It tends to delve into all of the details that the media just glosses over:

http://scotuswiki.com/index.php?title=United_States_v._Comstock