Perhaps there are to additional settings needed:
(1) An additional option could be added under Preferences > Privacy > AutoFill Passwords to "Never ask to remember passwords". This would enable people to bypass Orion's password save prompts without disabling autofill from passord providers.
(2) A toggle under the site settings (currently accessible by right-clicking on the URL, or in Preferences > Websites) to selectively enable/disable the "remember passord" functionality per-site. This would allow folks who had disabled password saving for a given site to quickly re-enable it.
By combining (1) and (2), power users could have some sites remembered by Orion and others remembered only by their preferred password provider.