> If you're using GA to get insight about your website, it would be somewhat useful, but not really - because GA would not be able to correlate the cookies to figure out the demographics, etc (and I don't know how much it would trust Via / Proxy-for headers, so other statistics it gives you are also limited).

A proxy can send whatever cookie it wants to the server (a proxy can actually hide the fact it's a proxy and make itself look like a normal client).

However a lot of GA's stalking behaviour relies on having cookies on a specific Google-controlled domain. The proxy using a different domain means it won't be able to neither access nor set those cookies. Good for privacy but obviously (and thankfully) bad for the author's nefarious goal.