The concern isn't that they use Cloudflare. The concern is that they're spidering the Internet, and therefore might be storing cached data that Cloudflare leaked.

while the internet archive / wayback machine do spider, I think archive.is only archives a site "on demand"

Yes but with all the people and even automated 3rd-party scripts making use of archive.is, it is practically a spider.

No TLS on this site?