There are no requirement about secret strings beeing random. In fact, I predict that they will be clear text passwords most of the time.
The do-not-swap feature is something I've been bringing up now and again, but it really isn't the main feature of secret strings. Neither is hiding secret strings from the rest of the Pike process. The absolute main usecase is making sure they are not printed in a backtrace on a webpage somewhere. Everything else is possible bonuses.