It’s still weird that they (CA/B forum) chose to include the port reserved for Simple File Transfer Protocol (RFC 913). I keep trying to think of charitable explanations, and perhaps some day I’ll see if I can find an archive of their pre-ballot discussions in developing those rules, but it leaps out at me as an error.
Simple File Transfer Protocol is this really archaic (hence the three digit RFC number) insecure protocol from the dawn of the Internet. But, it shares its initials with SFTP, a secure modern file transfer protocol that is implemented as a sub-protocol of the Secure Shell (SSH) protocols, and thus has no well-known port of its own. So I think that’s their mistake, but I can’t believe it survived not only the drafting process but even subsequent pre-ballot and ballot examination by all the supposedly noticeable CA/B representatives.