Safari Can't Open the Page (Persistent Certificates Problem in Safari)
I ended up solving this issue on my machine by following these instructions which seem to be different for 10.12 vs. prior versions of OS X. To summarize:

OS X 10.12

sqlite3 ~/Library/Keychains/*/ocspcache.sqlite3 'DELETE FROM ocsp;'


For OS X 10.11 and earlier

sudo rm /var/db/crls/*cache.db