There's a link further down but tldr, he ran a department that struggled to disperse unemployment benefits to the people of New Mexico during 2021. Hard to say if anyone else would have done better in his place, but his address and family info were getting shared online and a car got blown up at his place of work.
I understand the anger (but not to the point of terrorism or threats), but it's also pretty obvious to me that blaming one guy for the failures is kind of missing the point. The entire unemployment system has been deliberately undermined for ideological reasons, with the goal being making it as hard as possible to get and keep benefits. It's not shocking that one person could fix a decade or two worth of systemic rot when suddenly the system is strained to the max.