This is a hostmaster error, not a user error. Why doesn't Pair have a cert? As they don't; why is perlmonks forcing a secure connection? Letsencrypt ( letsencrypt.com ) has been providing them FREE for at least a year, and they're accepted by all the major browsers. The entire process can be accomplished in some 20 minutes -- even for a large hosting outfit. I managed the whole process in 15 minutes, with ~120 hosts.
IMHO this is a fairly serious matter; as when most users encounter the "frightening" message from their browser, will leave, and quite probably never come back. :-(
¡λɐp ʇɑəɹ⅁ ɐ əʌɐɥ puɐ ʻꜱdləɥ ꜱᴉɥʇ ədoH