The Symantec Threat Protection Service virtual machine is vMotioned by VMWare as a part of Storage DRS on a shared datastore causing:

• ESXi hosts to purple screen in NSX environments.
• SVA's to be randomly deleted in vShield environments
   

The vMotion of the SVA causes ESXi hosts within the cluster to Purple Screen.

In a VMware environment with vShield  the SVA is removed by DCS.

According to VMWare service virtual machines should not be vMotioned.
However at this time VMWare does vMotion the SVA if deployed to a Storage DRS enabled datastore cluster.

Set the datastore cluster to be Manual Only for the Storage DRS setting.

This allows Storage DRS to make recommendations but does not automatically vMotion virtual machines.

Then, if Utilized space is needed to be balanced, you can choose which virtual machines are Migrated.