I loathe Fb as much as anyone, but if you're just looking to make money their stock is the biggest 'buy' on Earth. Their numbers only get better in the face of bad news, they've barely started tapping the potential revenue from Ig, and they haven't even begun to monetize Whatsapp.
It's hard to say that MS was hurt by the DOJ given their current market cap.
Also, the US federal government is a shambles. They can't put together an inquiry on what lead to the seat of government being literally overrun, so I'd be incredibly surprised if they managed to take action against one of the most well funded entities on earth.
You forget DOJ and the entire executive branch it reports to are pretty much bought by lobbyists, many of whom directly or indirectly work for FB and other big tech.