[SalesForce] Using AMPscript/SSJS how do you unsubscribe a subscriber from a child business unit

My goal is to create a page that passes a business unit id and a subscriber key. The page sits on the parent/enterprise business unit, it will receive business unit ids from a child business unit. Upon clicking submit the page performs a master unsubscribe for that subscriber at the business unit level, but does not perform an enterprise level global unsubscribe.

I've gone through a few iterations.

My first attempt I landed on something like this:

<script runat="server">
  Platform.Load("Core","1.1.1");

  try {

    var isSubmitted = Request.GetFormField("submitted") === "submitted";
    var subscriberKey = Request.GetQueryStringParameter("skey");
    var publicationListId = Request.GetQueryStringParameter("pid");
    var businessUnitId = Request.GetQueryStringParameter("mid");

    var subscriber = Subscriber.Init(subscriberKey);
    var subscriberDEs = DataExtension.Init("ent._subscribers").Rows.Lookup(["SubscriberKey"], [subscriberKey]);

    if (subscriberDEs[0] !== undefined) {
      var subscriberEmail = subscriberDEs[0]["EmailAddress"];

      var hasSubscribedByListId = {};

      if (isSubmitted) {

        if (businessUnitId === "012345678" ) {
          var status = subscriber.Unsubscribe();
        } else {
          Redirect("https://urlForChildBusinessUnit.com/redirectPage?skey=" + subscriberKey, true);
        }

    } else {

      // no subscriber found
      Write("<br /><div class=\"tab-content\"><b>Your subscription was not found.</b></div><br />");

    }

  } catch(ex) {

    Write("An error has occurred: " + Stringify(ex) + "<br />");

  }
</script>

That solution would necessitate each child business unit having something like this to redirect to and make the business unit master unsubscribe:

<script runat="server">
  Platform.Load("Core","1.1.1");

  try {

    var subscriberKey = Request.GetQueryStringParameter("skey");
    var subscriber = Subscriber.Init(subscriberKey);
    var status = subscriber.Unsubscribe();

    // redirect back to a pretty unsubscribe page
    Redirect("http://parentBusinessUnit.com/unsubscribeconfirm", true);

  } catch(ex) {
    Write("An error has occurred: " + Stringify(ex) + "<br />");
  }
</script>

That works fine, however, it feels a little hacky using a redirect like that. Plus, if another child business unit is added in the future then you'd be revisiting this code.

With that in mind, I tried to see if I could come up with a better solution by incorporating AMPscript. I was able to update a subscription to a publication list on a child business unit, so I tried updating the all-subscribers list for a business unit like this:

%%[

  var @publicationListId

  SET @subscriberKey = RequestParameter('skey')
  SET @businessUnitId = RequestParameter('mid')
  SET @submit = RequestParameter('submitted')
  SET @radio = RequestParameter('unsubscribe')

  SET @subscriber = CreateObject('Subscriber')
  SetObjectProperty(@subscriber,'EmailAddress', @subscriberKey)
  SetObjectProperty(@subscriber,'SubscriberKey', @subscriberKey)

  SET @client = CreateObject("ClientID")
  SetObjectProperty(@client, "ID", @businessUnitId)
  SetObjectProperty(@client, "IDSpecified", "true")
  SetObjectProperty(@subscriber, "Client", @client)

  IF @submit == 'submitted'

    // set of ifs to find the all-subscribers list or find a clever way to retrieve it
    IF @businessUnitId == '123456789' THEN
      SET @publicationListId = 456
    ENDIF

    SET @list = CreateObject("SubscriberList")
    SetObjectProperty(@list, "ID", @publicationListId)
    SetObjectProperty(@list, "Client", @client)
    SetObjectProperty(@list, "Status", 'Unsubscribed'))
    AddObjectArrayItem(@subscriber,"Lists", @list)

    SET @update_list_sub = InvokeUpdate(@subscriber, @update_sub_status, @update_sub_errorcode)

  ENDIF

]%%

Despite the status returning that the update was successful, the user is still subscribed.

My next attempt I used code borrowed from a post at sprignaturemoves.com post that detailed injecting an unsub event into the LogUnsubEvent platform table.

%%[

SET @submit = RequestParameter('submitted')
SET @subscriberKey = RequestParameter('skey')
SET @businessUnitId = RequestParameter('mid')
SET @reason = "Business Unit Unsubscribe"

IF @submit == 'submitted' THEN

   var @lue
   var @lue_prop
   var @lue_statusCode
   var @overallStatus

   /* create a request to inject an unsub event into the LogUnsubEvent platform table */
   SET @lue = CreateObject("ExecuteRequest")
   SETObjectProperty(@lue,"Name","LogUnsubEvent")

   /* define and associate Subscriber Key to the request */
   SET @lue_prop = CreateObject("APIProperty")
   SETObjectProperty(@lue_prop, "Name", "SubscriberKey")
   SETObjectProperty(@lue_prop, "Value", @subscriberKey)
   AddObjectArrayItem(@lue, "Parameters", @lue_prop)

   /* define and associate unsub reason to the request */
   SET @lue_prop = CreateObject("APIProperty")
   SETObjectProperty(@lue_prop, "Name", "Reason")
   SETObjectProperty(@lue_prop, "Value", @reason)
   AddObjectArrayItem(@lue, "Parameters", @lue_prop)

   /* finally, you invoke the request */
   SET @lue_statusCode = InvokeExecute(@lue, @overallStatus, @requestId)

ENDIF

]%%

That worked the same way SSJS's subscriber.Unsubscribe() works, performing a master unsubscribe for the business unit that the page resides in or a global unsubscribe if the page belongs to the enterprise/parent business unit. Perhaps it's possible to include a client id into that LogUnsubEvent? I tried to add client id the same way subscriber key is added, but it appears to have no effect.

I feel like I'm either really close and missing something obvious -or- there isn't a way to use SSJS/AMPscript to perform a master unsubscribe from a business unit on a single page. Any help would be appreciated! Thanks!