Any U.S. citizen or resident, as well as any business or organization, including federal, state, and local government with a bona fide presence in the United States can register a .US domain name. One of the following three eligibility requirements must be met:
A natural person (i) who is a citizen or permanent resident of the United States of America or any of its possessions or territories or (ii) whose primary place of domicile is in the United States of America or any of its possessions, or
Any entity or organization that is incorporated within one of the fifty (50) U.S. states, the District of Columbia, or any of the United States possessions or territories or (ii) organized or otherwise constituted under the laws of a state of the United States of America, the District of Columbia, or any of its possessions or territories, or
An entity or organization (including federal, state, or local government of the United States, or a political subdivision thereof) that has a bona fide presence in the United States.
Not sure under which rules do having a server comes?
But he could have an entity in US already or can even get a US entity for such a name as it not too expensive (many states in US have <$100 fees of incorporation)