The problem is this is direct trademark infringement. The trademark is for a business, and will have overlap with Facebook. Facebook can try and argue that the trademark is invalid, but at the end of the day if meta.company can defend the trademark, there is going to be a settlement because renaming AGAIN isn't going to be very desirable. This could cause an Apple Records vs Apple Computer case where certain businesses are restricted for facebook.
However as both history and this event shows, facebook will just plow ahead and pay the costs later. Given opportunity costs, and everything, it likely is the most economically rational move. Having so much money that they know they can cover any verdict / settlement, and having limited - no personal liability at the director level, facebook can continue to act unconscionably. The only way you will stop them acting like this is to either extend the liability to management or so oversized and unreasonable punitive damages that they actually take a step back.