It is, and it would have been illegal for any Facebook employee with a ham radio license to use ham radio to contact another employee for any business reason during the outage. We don't have any evidence that that happened.

Where I live there is a General Motors amateur radio club. The club is not owned or run by GM, but GM sponsors it by allowing repeater equipment on top of their building, and presumably monetary and other donations over the decade. Many of the members are current and former GM employees but you don't have to be affiliated with GM in any way (or even have an amateur radio license) in order to join.

There are lots of amateur radio clubs associated with a company for sponsorship/community outreach reasons, I assume the Facebook one is the same. (And I have to assume because they don't seem to have a website that I could find.)

To reply to another comment in this thread, you can break nearly all FCC rules if you need help in a life-threatening situation. Facebook being down was NOT a life-threatening event as defined by the FCC, even if their services being unavailable indirectly lead to loss of life.