Priority boarding is not a benefit of oneworld Ruby.

However, BA choose to allow priority boarding (Fast Track) to oneworld Ruby on their flights, as do some other airlines.

This explains why it wasn't printed in the oneworld section in the magazine. I suspect the ground information at FCO just hasn't been updated. At some airports, half of the branding is correct and half not (eg. the banner and the little sign on the barrier post are different at MAD).