Argument validate incorrectly runs even if disabled

Okay before submitting the patch I wanted to make sure my proposal was consistent with how this was handled in other cases where an option's value is only relevant depending on another option... So I checked title_enable vs title.

It looks like in that case, 3 things are happening:
1. Something analogous to what I proposed (acting on title only if title_enable is true)

        // Test to see if we should use this argument's title
        if (!empty($argument->options['title_enable']) && !empty($argument->options['title'])) {
          $title = $argument->options['title'];
        }

2. Forcing consistency of 'title' based on 'title_enable' when saving the options form:

    // Clear out the content of title if it's not enabled.
    $options =& $form_state['values']['options'];
    if (empty($options['title_enable'])) {
      $options['title'] = '';
    }

3. The reverse of #2 upon loading the options - overriding 'title_enable' in the event that there's a title:

    if (!empty($options['title']) && !isset($options['title_enable'])) {
      $this->options['title_enable'] = 1;
    }

Do we want to do the same in this case? Is there anything else I missed while searching?

Thanks!

#1808824: Default validation criteria for a contextual filter can be wrong is probably also a symptom of this.