RDR
You may be right.
However, people have been hours/turbine-time building in LA with both Commander Chuck (Fullerton) and the other traffic watch operation (Van Nuys) for many years and I've never known anyone to be prosecuted for doing it.
Many UK pilots have flown with both operators over the years. As far as I know, the UK CAA has always taken a sensible line and has never rejected the hours for the purpose of 'qualify hours' - perhaps because the pilots have done just a few hours rather than as an ongoing unpaid 'job'.