Have you ever thought of having a different script for your edit form? Instead of running all of these functions on your edit form, you could simply find the Subscriptions in the DOM and remove all of the unnecessary emails from the left instead. You could use something similar to:
var $subscriptionOptions = $("select[title='Subscribers possible values']").find("option").filter(function(e){ return this.title !== "25 - Created by moi"; //or an email addy. }).detach();
That should work if you are wanting to trim the options to leave just the one email address. Since it will *not* be present in the *possible values* control, all of the options will simply be removed from the DOM.
Cheers,
Matthew