SETI Protected Antipode Circle at United Nations

The far side of the Moon or the Earth Moon L2 point are not totally RFI free even now. There are 3 satellites orbiting the Sun Earth L2 point and 2 more will be there within a few years. If you go out and look at a full moon some night, those satellites are out there about 10 times as far as the Moon and very nearly directly in line with it. Whatever communications they're sending to Earth are RFI on the Moon's far side.

I personally think an asteroid would be better. It would provide enough mass for a stable base and some portion of the construction materials, while having a low enough gravity field that the cost of landing those materials which would have to be supplied from Earth would be small. The distance from the Earth Moon system would mean only a small pointing area would be RFI prone, and that area would be moving relative to the distant stars. The very low gravity field would also allow a large structure with much less stress than even on the Moon. The chosen asteroid should have a suitable rotation rate to provide automatic scanning relative to its axis, a telescope would only need to drive its pointing in North - South declination to provide scanning of almost all the sky.

3 satellites orbiting the Sun Earth L2 point Joe

Yes, Joe, but...

Moon and his radio quiet cone on the Farside orbiting around Earth.
Sun Earth gravitational system L2 point are NOT Earth Moon gravitational system L2 point.