I've always kinda liked the idea of being able to give your allies a barricade that won't screw them over by blocking their shots or killing them with their own rockets, but due to how badly Citan's had to be nerfed to make it not oppressive in PvP, you're basically just trolling if you try to use it in PvE. A few simple changes to make it more viable in PvE would be to give it damage resistance against combatants, to make up for its reduced health, and allow combatant kills made through the barricade to reduce its cooldown. Pretty simple changes that wouldn't affect PvP, but would allow a previously PvP exclusive exotic to see some viability in PvE.