'Notify all' button with autocomplete field

Currently, when the number of users available to be notified passes the set limit, the checkboxes are replaced with an autocomplete field. Unfortunately, this also removes the 'notify all users' checkbox.

Is it possible to preserve the 'notify all' checkbox when using the autocomplete field?

Here is the original issue where the 'notify all' checkbox was added: #714918: Add 'notify all' button One commenter mentions that this might be fixed by allowing the use of a select box instead of an autocomplete field.