The optional for the Mirror Event is "weaken Terran Escort group". But there are no Terran Escorts in the mission. I don't get it.

There are four Satellites on the outer edges of the map, you'll see the blinking lights. Go near them and interact to start uploading a virus that makes the Damaged Staadi ships in phase 2 severely damaged and go down like a sack of potatoes. Keep in mind, unless a group (Alpha, Bravo, Charlie, and Delta) are busy fighting, they'll break formation and go to their specified Satellite and kill the uplink. Think of the map as a large X, the middle is where the Flagship spawns, the inner part is each group, and the tip is each Satellite.

I know how to do it; I just don't get why there are no Terran Escorts in the mission.

He's trolling.

Either he's implying that there are no prostitutes, or that he's ignorant of the fact that Escort can be used as a type of ship or as the act of protecting someone something... ya know ESCORT it.

I've encountered this once too often over the last week, people playing ignorant over word meaning just for lolz.

I was referring to Terran Escorts, as in starships. I guess I had overlooked the escort role itself.