First and foremost, I think the ruling is a mistake; there's nothing in the Constitution which would extend the protections afforded to US citizens to foreigners, especially those actively opposed to the US. The court is creating new Constitutional protections, and that's not their job. Moreover, the new protections are going to be nothing but trouble for the military in the future, and one of the worst things we can do as a country is make it more difficult for our military to keep us safe.
That said, I think Bush shares at least half of the blame for this idiotic ruling and precedent. As a blame Gore for politicizing Global Warming, turning it into a partisan battle, and thus allowing people to compartmentalize any actual evidence as political propaganda, so I blame Bush for creating a situation which forced the Supreme Court to make this ruling.
It is against international law, and the spirit of America, to hold anyone indefinitely without a trial, the ability to rebut accusations, and ultimately seek justice for persecution. In holding the prisoners in Guantanamo indefinitely, the government was creating a situation which was morally reprehensible both to the international community and the domestic populace. Yes, the situation was abnormal: the prisoners didn't have a sponsor nation they could be released to, nor a formal army to claim allegiance to and thus appeal to be treated as prisoners of war, nor even a formal war to be prisoners of (other than the nebulous "war on terror"). Nevertheless, the US government did not do enough to avoid to perception of holding people indefinitely, nor did they offer any end-time conditions.
As such, the Supreme Court of the US was the last resort against the morally reprehensible situation the Bush administration caused. They needed to do something, and they did; the consequences will be bad for the country, but it was an inevitable (and foreseeable) consequence of the handling of prisoners at Guantanamo Bay. Shame on the Bush administration for creating this situation and this precedent.