In this specific case, the bug with the Realtime API didn't prevent apps from accessing data about likes, posts and comments on pages - those were always query-able via the API on demand. That, along with our understanding that this issue affected only apps subscribed to updates on page content, meant we didn't, on this occasion, classify the bug as within the 48-hour SLA. We're constantly listening to our community, and may revisit how we classify and prioritize issues like this going forward.
I'd like to hear a detail postmortem.