I tried to look up their site then realized I block "us.to" locally. Since you have their site linked in this thread they are likely seeing the HN thread as a referrer in their access logs and reading this. I expect this to turn into an ongoing battle as a result, but maybe this could be a fun learning exercise for everyone here.
The current IP 45.86.61.166 is likely a compromised host [1] which tells me you are dealing with one of the gangs that create watering holes for phishing attacks and plan to use your content to lure people in. They probably have several thousand compromised hosts to play with. Since others mentioned you could change the content on your site, I would suggest adding the EICAR string [2] throughout the proxied content as well so that people using anti-malware software might block it. They are probably parking multiple phishing sites on the same compromised hosts [3].
This would also be a game of whack-a-mole but if you can find a bunch of their watering hole sites and get the certificate fingerprints and domains into a text file, give them to ZeroSSL and see if they can mass revoke them. Not many browsers validate this but it might get another set of eyes on the gang abusing their free certs.
If you have a lot of spare time on your hands, you could automate scripting the gathering of the compromised proxy hosts they are using and submit the IP, server name, domain name to the hosting provider with the subject "Host: ${IP}, ${Hostname}, compromised for phishing watering hole attacks". Only do this if you can automate it as many server providers have so many of these complaints they end up in a low priority bucket. Use the abuse@, legal@ and security@ aliases for the hosting company along with whatever they have on their abuse contact page. Send these emails from a domain you do not care about as it will get flagged as spam.
Another option would be to draft a very easy to understand email that explains what is occurring and give that to Google and Bing. Even better would be if we could get the eyes of Tavis Ormandy from Google's vulnerability research team to think of ways to break this type of plagiarized content. Perhaps ping him on Twitter and see if he is up to the challenge of solving this in a generalized way to defeat the watering holes.
I can think of a few other things that would trip up their proxies but no point in mentioning it here since the attackers are reading this.
[1] - https://www.shodan.io/host/45.86.61.166
[2] - https://www.eicar.org/download-anti-malware-testfile/
[3] - https://urlscan.io/result/af93fb90-f676-4300-838f-adc5d16b47...