Not admitted; accidentally told the truth.
But since he's a bumbling stumbling old man who forgot the word for "God", nobody really holds him accountable for anything.
What's curious to me is how you didn't tie that very statement as Biden throwing Obama under the bus, which is what Biden actually did.
The expatriating act must be voluntary and take any of seven forms.
Committing any of the following acts will create a presumption that it was performed voluntarily with the idea of giving up U.S. citizenship, although the person might later be able to rebut (disprove) this presumption:
Becoming a naturalized citizen of another country after age 18.
Formally declaring allegiance to a foreign government after age 18.
Accepting a position in the government of another country after age 18, if one has citizenship in, or declared allegiance to, that country.
Joining the military force of another country either (1) in any capacity if that country is engaged in hostilities against the U.S., or (2) as an officer.
Formally renouncing U.S. nationality abroad before a U.S. diplomatic or consular officer.
Formally renouncing U.S. nationality in the U.S. when the U.S. is at war, if done in writing and with the approval of the U.S. Department of Justice.
Being convicted of treason or participating in any attempt to overthrow the U.S. government.
https://www.nolo.com/legal-encyclopedia/when-us-citizens-can-lose-us-citizenship.html
If you listen to the clip, right before he admits/slips that they have the largest voting fraud organization, he says it goes back to Obama too.
The or and then the "participating" would be done first. Detained and Arrested and Convicted and Imprisoned all have their own rules to satisfy.
The son of the what now?