From The Washington Post:

“Bossert, Joyce, and now Nielsen,” Paul Rosenzweig, a former top DHS policy official, told me. “I am sure the professional staff will continue to do their level best and there is no reason to think that McAleenan is not willing to engage. But at the same time the lack of high-level commitment to the issue is evident.”

And here’s former DHS cybersecurity official Paul Rosenzweig who did some research on the figure but still couldn’t find a definitive origin.