That's only a matter of degree if you declare the battlefield to be whatever suits you.
(Admittedly, most terrorists don't meet this criteria, and are therefore spies/saboteurs with none of the rights of POWs.)
I just find it hilarious that US journalists would focus their attention on China's political infractions when some really bad #$&%! is still going on in our country. After Obama got elected he still hasn't restored the rights that Bush took away from us. Mainstream US media should spend more time on that. I don't know what's so interesting about this article; it's not like Communist China turned into a totalitarian gov yesterday.
However, this man is very important to China, even though the dunderheads who have stitched him up don't seem to realise that. His detention is a blow to China's credibility and a vast embarrasment to those in the government who are genuine about the rule of law. It is also very bad for Chinese business! His group's penetration of the poisoned milk scandal saved lives, and brought callous criminals to justice.
Hardworking, independent public defenders like Xu Zhiyong are going to be an ever more essential part of the Chinese economy in the future, and to imprison him for imagined crimes against the state is not simply unjust, it is self-defeating!
Of course communism had the appeal of being a non-racist ideology, so a lot more innocent (but extreme naive) people got tangled up when HUAC went after the communists. That being said, they're both totalitarian ideologies: I wouldn't want either Nazis or Communists holding public office in the United States, nor do I have any issues with private employers firing either (at least in employment-at-will states).
At that time China was going through Great Leap Forward (mass artificial starvation, with millions dying) and (in the 60s/70s, after HUAC has died down) cultural revolution. Again, a very blood period.
As for illegal detention, I am pretty squarely against it: either these people should be held as POWs or be tried as criminal defendants. Yet illegal detention that happens on the battlefield is much different from illegal detention of a political activist working within the system. If you want to compare apples to apples, I'd look at China's treatment of US prisoners during the Korean war or their treatment of their own Islamic extremists in Xianjing province (yes-- there are real Islamic extremists targeting civilians in China and no, they're not "freedom fighters").
That being said, it's a silly comparison to do irrespective: provided US was as flagrant about human rights as China, that doesn't justify China treating their citizens in the same fashion. Nor does China treating their citizens horribly justify human rights violations by the US. The original article did not claim anything along those lines. Arguing that "two wrongs make a right" is logically fallacious and morally bankrupt.