you are a required crew member by regulation and the FAR states that you must log this as PIC. Both of you. The IAA, German and Czech CAA accept this, seems the UK CAA doesn't.
If may be of limited value with regards to your own skills (the safety piloting time that is), but it is perfectly legal and airlines are most definitely interested in your total time. Nobody ever asked me if these hours were flown as safety pilot or not, but they all ask for the TT!
cheers, IP