Legislation only has jurisdiction where it has jurisdiction--usually within the borders of the state represented by the legislating body. That's just a matter of practicality, and even that fortunately is not always adhered to by the US as when it supports foreign insurgents or leaders that are deemed more likely to uphold the natural rights of individuals.
The justification for this nation, the argument for its legitimacy, is described in the Declaration of Independence as an observation of nature "self-evident" and not something that is to be arbitrarily stipulated by some deliberative body. For any government, and the US Constitution, to be founded in truth it must be consistent with nature.
Thus, either the U.S. is illegitimate by the standards of the DoI or else the Constitution is consistent with the fact "that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness."
So, yes, Englishman in England have the right to life, liberty, and the pursuit of happiness, whether or not anyone is able to protect those rights. It is too bad that the US cannot protect everyone's rights, but it can protect the rights of everyone within its borders. You seem to be arguing that since the US cannot protect all people's rights, it should be allowed to violate the rights of some.
It is up to Iraq to protect a visiting Iraqi-citizen's natural rights. Iraq may choose to do this with an international agreement, which we should hold our govt. to, if it makes such an agreement. But when a non-citizen here can be deported, he has no liberty, much less rights under the Bill of Rights, here in the US. Before we deport him, we can bug his apartment without a warrant, without worrying about any rights he might try to claim under the BoR. If that bothers him or his country, he should leave, or they should conquer us, if they can.
A visiting Iraqi citizen has an inferior claim to the protections of the Bill of Rights. That's all I'm saying.
No radical extensions of protections should be provided to just any lowlife, just because he happens to be inside US borders.
Similarly, I don't expect my natural rights to be protected by foreign countries I may be visiting. I might like them to, but they owe me nothing, unless their Constitution or laws say they owe me something.
Our Constitution was written for the posterity of the people who are OF the United States, not non-citizens who are visiting.