It is because many DDoS websites sitting behind Cloudflare are FBI run. See titaniumstresser[0] as an example. One of their sub-domain's IP address is allocated to the FBI[1]. Seems like the longest lasting sites peddling stolen info, child pornography, or malicious services are all run by feds.
Hostname: direct.titaniumstresser.net IP Address: 153.31.25.12 Organization: FBI Criminal Justice Information Systems