Initial response from my MS ticket is below. I have shot back a few questions to the person.

I would like to share this update with you that talks about an update causing unplanned reboot.

The KB3172605 was originally released by Microsoft in July 2016, at which time it was deployed using SCCM. However, Microsoft revised the patch on September 13 2016, but SCCM automatically re-installed the patch on our clients and caused unplanned reboots.

The issue is because of a change in the Update classification from being published as “Optional” in July to “Recommended” . There was also a package churn with higher version of ntdll.dll binary to fix one of the issue that was found after initial release in July 21st. This is what triggered installation of the same KB and caused unplanned reboot.

If we have standalone WSUS The workaround is:

Automatic Approvals - Advanced - Revisions to Updates - Automatically approve new revisions of updates that are already approved

At this time this is the expected behavior however, our development team is still working on it.