Seeing this event and rebooting on our 2008R2 systems as well. We had patched servers with LANDESK and rebooted them, and some of the server rebooted with this event 12 hours later (outside of the maintenance window in agent settings). Default server Agent settings are also Never Reboot.
The process C:\Program Files (x86)\LANDesk\LDClient\vulscan.exe (SQLSERVER) has initiated the restart of computer SQLSERVER on behalf of user NT AUTHORITY\SYSTEM for the following reason: Legacy API shutdown
Reason Code: 0x80070000
We are running LANDESK Management Suite 2017.3.2