Resolution
As a useful workflow step,Access Governance Suite allows emailing comments from a work item's decision (rejection or approval).
Since Access Governance Suite 4.0 release, workflow logic updates a variable with work items' comments.
The (custom) workflow needs to define/to pass the "workItemComments" variable
to the email template, as demonstrated in this code fragment:
<Workflow ...>
...
<Variable name="workItemComments">
<Description>
Global comments accumulated during the workflow which should be shared
with other approvals. When a new approval is created, the comments in this
list will be added to the work item.
</Description>
</Variable>
...
<Step action="call:sendEmail" icon="Email" name="Send Rejected Email">
<Arg name="template" value="myDummy Role Rejection Notice"/>
<Arg name="lastWorkItemComment" value="ref:workItemComments"/>
<Transition to="Audit Failure"/>
</Step>