Yes this seems strange, I can only assume that it means the devices will still function accurately despite any US GPS degradation (eg around military installati

Yes this seems strange, I can only assume that it means the devices will still function accurately despite any US GPS degradation (eg around military installations, sensitive events etc), ie they will no longer be under US control. But that would apply whether they are multi-system capable, or just that they can read the other systems, and are not entirely dependent on GPS.