Probably not "fake news". As to the legality of the shooting...well, it's Mexico. Someone pointed out in that twitter thread that this was a Latin American country. Life is cheap. If you have to shoot a guy and don't kill him and he lives, he may hold a grudge for a very long time. And who wants to be looking over his shoulder the rest of his life. Of course Red Shirt might have relatives too. While I think it was overkill, different country, different rules. Not so litigious as the U.S...food for thought.
What started as an argument in a canteen , quickly turned red when a man pulled out a gun and was later disarmed and killed by his own weapon.
At the moment the location of the events is unknown, however, it is known that the establishment is located in some state of the Mexican Republic.
In the video you can see how the subject orange shirt shows a gun -type bracket in a threatening manner. Moments later he was shot down by the cap guy, who took his gun and opened fire on him.
After 5 detonations of the firearm, the individual dressed in orange was lying on the ground, apparently lifeless.
Moments later, it can be seen as the shooter returns to pick up an object Bar bar to finally leave the scene of the crime.