Since his retirement in September 2019, Admiral Nielson has been involved in a wide range of lectures and studies on the topics of digitalization, AI, cybersecurity and demographic developments in Germany and the resulting consequences for Germany and NATO. Among others, he collaborated on a study of the Henry Kissinger Professorship "Partnership in Leadership", as well as on the "GLOBSEC Adaptive Portfolio: Catalyzing NATO's Performance Through Innovation."

In addition, he was appointed by NRW Minister of the Interior Reul to a team of experts for the development of future concepts for flood disaster control. The final report was submitted to the minister in February 2022. The first measures, such as the warning app, were successfully tested in December and are to be implemented quickly.
Since September 2021, Admiral Nielson has been working for the Montag Foundation on the Citizens' Council on Education. At the end of 2021, a comprehensive immediate program was completed and presented to the State Ministry of Education in February 2022.