Nelson said Treasury has not responded to his application to be taken off the list since he filed it two years ago.
Treasury spokesman John Sullivan said people are taken off the list, but he did not immediately respond to questions about whether al-Buthe's request to be removed had been received or why Nelson has received no response.
The reasons al-Buthe was taken off the U.N. list were not given by the committee, which said in a statement only that it considered a request submitted through the committee's ombudsperson, and the ombudsperson's comprehensive report.
Kimberly Prost, ombudsperson for the Al-Qaida Sanctions Committee, said al-Buthe was the 21st applicant to be taken off the list, made up of more than 350 people and organizations. Two others whose cases have been reviewed were not. She said her report was confidential and she could not disclose its contents.