Cannot save user account information with fbconnect enabled

When I enable the fbconnect module, edit any field and click save, I get the following message:
Detected malicious attempt to alter protected user fields.
and it will not allow the values to save.

I've tracked it down to in the fbconnect.module, if I comment out

      $form['uid'] = array(
        '#type' => 'hidden',
        '#value' => arg(1),
      );

the error goes away.

This is on Drupal 6 latest dev (Feb-21)