I do not represent Cloudflare or Cloudflare’s views. You should read their TOS and Abuse policy.
Based on the abuse policy and TOS listed above, Cloudflare does not prohibit pornography from being hosted on its service. The only exclusion is underaged (including CSAM) or non-consensual porn, in which you should immediately notify the website operator; you may also contact the FBI or your local crime authorities at any time if you believe illegal content is being hosted.
(My opinion): Instead of requesting takedown of pornographic websites, I suggest making sure the website has the Restricted To Adults (RTA) label somewhere on the page (usually found in the footer). This will allow parental blocking programs to safely and reliably block websites that display age-sensitive material. If a website does not have this when you think it should, you should contact the website operator about getting the label implemented.