ServerDNSAllowNonRFC953Hostnames affects clients, and AllowNonRFC953Hostnames affects servers
It looks like the code and man page entry for ServerDNSAllowNonRFC953Hostnames was copied straight from AllowNonRFC953Hostnames, which is the equivalent client option.
I think this is ok as-is, because even though both options affect both client and server, tor instances typically only run as clients or servers, not both.
However, the manual page entries could be updated to clarify that the options are synonyms, and affect both clients and exits.