I guess, in terms of preservation, about the same rules apply as for a citation and/or block quote. Meaning, clearly state that this is a quote and provide references to the original (so it can be identified). Include a statement of good faith, mentioning your willingness to revoke the content, should conflicts arise. (Also state why you found it important to preserve this, so it can be understood as a tribute to the original.) Do not monetize in any way.

The difficult question here is, if it's really a matter of preservation. The site/page isn't actually gone, it's just the certificate that has expired. The original content is still reachable, while jumping through a few hoops (i.e. browser dialogs). Still, following the guidelines provided above should somewhat mitigate the impact of any wrong doing.

Agreed, for a silly site that's not monetized (and neither was the original), then all that's at stake is credit.

Phew, I was briefly worried that the website in question was https://zombo.com :D

This is called a proxy server. You can take any domain, paid or free. You may want the domain to start with the word proxy, so that your users know that you are not copying the site, but using a proxy. You can use your own server or CloudFlare for your domain, with a DNS record CNAME. You can configure the proxy server to use http or https without checking SSL.

Have you checked webmaster info via whois for the domain? I know, it's generally obscured and all nowadays, but there might be a way to contact the author, if they aren't MIA.

There's absolutely nothing wrong with re-using an expired domain.

I'd even go as far as recommending it for hosting similar content to the previous owner's; in the same concept as cafes closing and re-opening under new ownership.

It's the site-squatters, domain-traders and link-farmers that shouldn't be allowed to take over existing URIs.

If my website stopped working, and someone spidered and preserved it, I'd be grateful.

Did the domain expire as well and you picked it up? If you created something similar the QR code would still point to the old (broken) domain

There be a similar alternative site yiu can link to? Are you able to share the broken site

In 1994, I had access to personal webpage hosting. I read the HTML doc and built a webpage and because URL's were a big idea for the web I linked to an external image. In a few weeks the link was broken.

That's just the way it goes when you try to use the web the right way. Working around it is probably pragmatically ethical. Perhaps not deontologically.

But it is not that complicated. If you don't feel it is ethical it is not ethical. Ethics is not doing things just because you can get away with them. Good luck.

im really wondering if you're refering to https://nyan.cat/

I assumed they were describing ytmnd

Link to the copy on archive.org instead?