You're right, I didn't think of the radiation flipping bits\melting stuff, but we could shield it. And to be fair we're talking about going for the bandwidth world (uhh... universe) record, not the data-longevity record. Just make it last as far as Mars or something.
The gold record will last way, way longer, as it's low density data, thus fairly redundant, and you could work around any micrometeorite holes.