He's not just complaining about the release schedule; he's complaining about the numerous and intrusive dialog boxes that pop up whenever Firefox's major version number is increased. Mozilla needs to remove every last one of those dialog boxes and make major version updates as silent as they are in Chrome.
He pointed out why that might not be possible. If an add-on is only supposed to work from version 3.6-6.0, and Firefox silently updates to 7, the user loses the add-on's functionality (and for many people, the only reason to use firefox are the add-ons)
When an add-on is disabled some sort of notification is desirable, but it doesn't have to come in the form of a modal dialog that blocks usage of the browser. There's generally nothing a user can do about it anyway. Furthermore, Mozilla could be doing a much better job of compatibility testing for the most popular extensions to ensure they don't have to be disabled every upgrade.
