The drag and drop are functionalities of the GUI/UI itself and do not have workflow triggers or actions associated with them. However, what you may be able to do is capture a workflow trigger that the drop and drop is triggering.
For example, if you are dragging an item to another folder, the TS_SUBJECT field should be changing. Therefore, there would be a FieldCanChange triggered on that field. You can set a condition in this workflow trigger to disallow the change.

Example:

If FieldName = ''TS_SUBJECT'' Then
If User.IsInGroup ''Limited_Group'' Then
Test_FieldCanChange = False
Else
Test_FieldCanChange = True
End If
End If