Re: Pointless Golden Record
Spectroscopic analysis looking for combinations of chemicals that suggest industrial activity rather than natural sources may find Extra Terrestrial Life, if we have a big enough space telescope. I'll be very surprised if a Radio Search works, even if we currently have 100,000 civilisations in the Milky Way using Radio. (assuming too they were using it x 100s or 1000s or 10,000s of years ago, the disk of the galaxy is about 100,000 light years across).
Space is like a quarantine system, for travel and communication, unless there is some sort of FTL Starships and Ansibles possible.