The original Nomad is an alternate identity which Steve Rogers adopts after he abandons the Captain America costume and title.
In Captain America #180 (December 1974) Rogers becomes disillusioned with the U.S. government when he discovers that a high ranking government official (heavily hinted to be the then President of the United States Richard Nixon) is the leader of the terrorist organization known as the Secret Empire.
Rogers then decides to abandon his Captain America identity, feeling that he cannot continue to serve America after this latest discovery has shattered his faith in the nation's status. Then, he realized that he cannot abandon a life of heroism, and he subsequently takes on the name "Nomad" (as it means "man without a country") adopting a new dark blue and yellow uniform with no patriotic markings on it at all.
This identity is short-lived, at the conclusion of Captain America #184 (April 1975) Rogers returns to the role of Captain America when he realizes that he could champion America's ideals without blindly supporting its.
In conclusion, if Marvel wants to include The Nomad to the MCU a perfect reason for Steve Rogers to leave the identity of Captain America would be Obama.