If the government can strip your citizenship away because of their suspicions of your ties to terrorism (ie, extrajudicially (ie, arbitrarily)) , then do whatever they want with you because you're no longer under the aegis of the law, enshrining the right of citizens to not be detained indefinitely seems kinda toothless (hey, wasn't that the status quo before the War on Terror?). If they want to do this to a citizen, they can dispel the protection by making the target not a citizen anymore.
All this is especially troubling because, as noted below, the Constitution, and other human rights legislation, typically extends protection to "persons".
But what's pointed out is that it only protects citizens. It clarifies, as there was a deadlock in the Senate over the issue before it, that non-citizens (other persons) or those no longer recognized as citizens (i.e. lost due to joining a foreign army or suspected of national security violations such as terrorism) do not have these protections.
The Constitution of course evaluates people as having these rights. It's a bit of a silly game to try to pretend that The Constitution is relevant today as it was written hundreds of years ago - but these differences are crucial. The placement of the boundary of habeus corpus - for all of the recent experimentation the United States has been doing with it - has been clarified by Lee-Feinstein as short of a protection for people and only a protection that extends to certain people under certain circumstances.
So, a person who is a citizen, could have their citizenship revoked for being a terrorist (by some definition) and then be detained indefinitely? Am I reading your, and the parent, comment correctly?
The amendment clarifies the boundaries of habeas corpus.
These boundaries apply only to particular people - namely those people with recognized US citizenship.
First, most of the human rights abused by the United States governments are non-Americans to begin with (let's put aside the penal system and some very sordid history with suppression of domestic civil rights groups for a second).
The amendment clarifies that foreign targets have no right to habeas corpus, a trial, to know even what they are being held for, etc. A very large contingency of innocent people suffer through this, but this isn't the comment to expound on it.
Second, the US can revoke citizenship of those it deems dangerous to national security (people like Snowden among them).
The criticism of the amendment is that the boundaries drawn do not respect the rights of "people" - only the rights of those for which it is convenient to respect (less than 4% of the people on Earth, and no serious dissidents, whistleblowers, etc).
All this is especially troubling because, as noted below, the Constitution, and other human rights legislation, typically extends protection to "persons".