Response from the PPRuNe Nerds:
If a link appears on PPRuNe (in a regular posting for example) and someone follows it to their site they then have that person's IP address and the fact they arrived via PPRuNe clearly visible to them in their server logs. So banning everyone that came to them via PPRuNe is easy.
Why anyone would set up a public web site to democratically promote their ideals, then block interested visitors, beats me!
Woomera