Not helping after joining a dive

Been seeing this a lot lately. I’ll be doing a solo dive with well over 15 minutes in and someone joins. This person then proceeds to not help out on the mission. Most recently I was doing a liquid morkite mission and this scout just stood on the platform not repairing the lines. I flagged them I spammed it even and he just continued to shoot glyphids not remotely close to where we needed to be. Not sure if green beard or not but as a pro tip: if you join a solo game you should help with the mission.