When you actually read that case, though, Kerr misrepresented Justice Brennan's views. Brennan's stance was not based on some fuzzy-headed citizen-of-the-world mentality but instead the argument that the Constitution imposes limits on government, not just the citizenry. From his dissent in Verdugo-Urquidez (citations omitted):
What the majority ignores, however, is the most obvious connection between Verdugo-Urquidez and the United States: he was investigated and is being prosecuted for violations of United States law and may well spend the rest of his life in a United States prison. The "sufficient connection" is supplied not by Verdugo-Urquidez, but by the Government. Respondent is entitled to the protections of the Fourth Amendment because our Government, by investigating him and attempting to hold him accountable under United States criminal laws, has treated him as a member of our community for purposes of enforcing our laws. He has become, quite literally, one of the governed. Fundamental fairness and the ideals underlying our Bill of Rights compel the conclusion that when we impose "societal obligations," such as the obligation to comply with our criminal laws, on foreign nationals, we in turn are obliged to respect certain correlative rights, among them the Fourth Amendment.So Brennan wasn't saying that the American government should be accountable to foreigners, he was arguing that it should be accountable to the Constitution. Verdugo-Urquidez was handed down in 1990, an example of the Supreme Court denuding the Fourth Amendment in deference to the drug war. There's a growing array of cases in which SCOTUS has eroded Fourth Amendment protections to make it easier for the government to prosecute and convict drug offenders, and this is an example where application of those precedents leads to unintended consequences.
By concluding that respondent is not one of "the people" protected by the Fourth Amendment, the majority disregards basic notions of mutuality. If we expect aliens to obey our laws, aliens should be able to expect that we will obey our Constitution when we investigate, prosecute, and punish them. We have recognized this fundamental principle of mutuality since the time of the Framers.