In any Change Workflow or Policy script event handler which is triggered by a Deprovision operation, any attempt to query Deprovision Status attributes will always result in a NULL or empty value being returned.
$value1 = $DirObj.Get("edsvaDeprovisionStatus")
$value2 = $DirObj.Get("edsvaDeprovisionReportXML")
Both of these values will always be NULL.
This is expected functionality.
Deprovision status attributes are only written after all Deprovision operations have been completed, including programmatic pre- and post-deprovision operations.
Use a Scheduled Task or Automation Workflow to periodically check query the value of Deprovision status attributes if desired.