Theming in drupalforfirebug_user breaking custom Admin theme

The function drupalforfirebug_user() makes a call to theme(), which is breaking the custom Admin theme functionality.

Some background: The custom theme gets set in the function system_menu(). Specifically, drupal fetches the 'admin_theme' variable, and assigns it to the global variable $custom_theme. Ideally, this is supposed to happen before any actual theming occurs, to ensure that the proper theme is set and used.

The problem: a module may invoke hook_user() before system_menu() is fired. In this specific case, it's leading to init_theme() being called before $custom_theme has had a chance to be set.

For example, during invocation of hook_init(), Organic Groups calls user_load(), which invokes hook_user(), which fires drupalforfirebug_user(), which calls theme(), which leads to init_theme() being called. Since the $custom_theme variable hasn't been set yet, drupal decides to use the default theme.

For reference, I've attached the relevant function stack below.

I'm not sure if there's a reasonable fix for this without totally disabling the "Users" tab functionality. Maybe only call the theming function if isset($theme) returns true?