BGP itself didn’t cause this problem. An operational error/bug/whatever that manipulated network configurations was the cause of the outage. BGP is just the messenger: if you misconfigure it your network will break, but it’s not BGP’s fault.

A more accurate checklist item would be “is it the network?”

The cause wasn't BGP though, it was just caught in the middle of a big mess and made it very hard to undo a botched config change.