The whole point was to put GALILEO on frequencies that overlap with military BeiDou and military GPS, so that no government could jam civilian GALILEO without jamming their own military tech.
The whole point of galileo is to have a system which is not dependent on the US and their GPS switch.
Jamming is a local action, the US will be able to jzm Gallileo like we are able to jam GPS - again locally.
Frequencies can be switched, if we only relied on the fact that they are the same then the US could switch theirs (and have equipment which is compatible if course) and there goes our security.
I work in security and have worked for 12 years for a huge provider of telecom systems and hinestly do not see any real advantages to match the frequencies.
Also, if we had the same frequency, WE could not jam GPS if we wanted to.
