Earlier quoted context omitted.
You seem to be implying that the domain was registered in response to the breach. Could it be that the anthemfacts.com domain was intended for a different use, or to prevent someone else from registering it, and was re-purposed after the intrusion to present Anthem's case? I don't know much about SEO, but quarantining negative information on a separate, immediately available domain might be the motivation here.
A domain name that is being used exclusively to address to data breach, and was registered within the past 2 months. And it's just a coincidence? Seems very unlikely. And I'm sure they're quarantining negative info on an unrelated domain, but why would they even need to consider repurposing an existing domain name, instead of buying one? We're not talking about somebody doing a side project and hoping to save a few b…
My point is that while it is used for that purpose now, that doesn't mean that it was registered for that purpose back in mid-December. Your theory about the breach occurring earlier and being concealed until now is certainly possible, but the domain registration date on its own is not supporting evidence.