No., he was already a citizen of Arkansas, Taking the Oath to the US disassociated himself from the Confederate States of America
and affirmed his loyalty to the United States.
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The Oath of Allegiance, also called a Loyalty Oath, was a document signed by persons during and after the Civil War to pledge loyalty and allegiance to the Union. Initially intended for employees of the Federal government and military personnel, the oath soon took several different forms and eventually extended to the state level. Employment and business ownership were then dependent on signed oaths.
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They Took The Oath Of Allegiance.
This page is of those who took the oath of allegiance they were soldiers and civilian, they were young and old men and women and children. They were prisoners of war or civilian that were arrested for one reason or another. A lot of people think that after they took the oath they were aloud to go home or where ever they liked that was far the truth, however some were aloud to go home. After they took the oath they were on parole and were not all that free to do as they liked. Some were ordered to a family home and not aloud to leave, or not to leave the county others were ordered to stay within the State they were paroled in and others were aloud to go to any State so long that it was a northern State. The Confederates also had a oath of allegiance I have not seen a full wording of it, but in my research I found it was about the same as the Unions with the same rules.
http://civilwarthosesurnames.blogspot.com/2008/01/they-took-oath-of-allegiance.html
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President Abraham Lincoln had introduced the idea of former Confederates re-entering the Union through an oath of allegiance before the Civil War was over. In 1863, Lincoln issued a proclamation, which offered to pardon most former Confederates who would swear to uphold the US Constitution and would reinstate any state into the Union once ten percent of its 1860 voting population took the oath and established a new government.
http://www.teachingushistory.org/ttrove/Oathofallegiance.htm