It shouldn’t be because you’re not actually the owner of the IP address. If any user could get a cert, they could impersonate any other.
They’re ‘shortlived’ 7 day certs, verified using a HTTP challenge. It doesn’t matter who owns the IP, it’s just a matter of who holds the IP.
Cloudflare usually blocks ‘unknown’ bots, which are basically bots that aren’t search crawlers. Also I’ve got Cloudflare setup to challenge requests for .zip, .tar.gz, or .bundle files, so that it doesn’t affect anyone unless they download from their browser.
There’s also probably a way to configure something similar in Anubis, if you don’t like a middleman snooping your requests.