Nielsen gained associate membership of the Green Party in 2013. In that year, he also ran for the Kings State Council, representing Beaverwick. Nielsen and another Green Party candidate, Surad Chand, ended up winning the two seats available for Beaverwick. He was also appointed as the Kings State Secretary for Finance and Business as part of the Kings State Cabinet of the 50th Kings State Council.
Throughout his life, Nielsen has been a fan of association football. He had a minor administrative position at the Newhaven Rockets from 2008 to 2010, and from 2012 to 2014 he was a press secretary for the Bay Hawks. In late June 2015, Nielsen was appointed as the head of the Lovian Football Association by Minister of Tourism and Sport and fellow Green Party member Levi Straszev.