My contention is that "owing" is not the same as "affirming," and that a citizen who has not sowrn an oath of allegiance to the US can be charged with treason. See Tokyo Rose, born in the US, not naturalized.
-- An American citizen does not necessarily owe allegiance but they are subject to the laws. --
What is the support for the contention that a US citizen does not, absent taking an oath, owe allegiance to the US?
Because legal terms in legal theory require precise definitions, the process of law cannot be executed without such precision, else the rule of law breaks down.
Notions of ‘allegiance’, ‘patriotism’, ‘loyalty’ are all amorphous in a variety of settings.
But certain positions in society need a visible, recordable, certifiable record of fact. Taking an Oath is the means to establish such fact in the context of allegiance.
Americans agree to pledge allegiance to the Flag or stand for its National Anthem. There is no law requiring such conformance. Although some kneel in protest of such symbolic acts, there is no law requiring them to do one or the other. But there is a social compact. There is a right for Americans to shun and disapprove of such kneelers to the point where the commerce is disrupted and the franchise leaders move to stanch the bleeding to their bottom lines. Pragmatism weighs in favor of social compacts.
But these are acts of populist America whereas certain other acts can harm the Republic and these harmful acts must be defined and dealt with. Hence, laws and affirmations by oaths are vital.