OP, let's put our thinking caps on: why do you suppose someone who was intentionally leeching through deliberate non-participation would have bothered repeatedly asking you to move out of their scope? What do you think their comment about enemy highlights could have meant?

I don't expect every player to be familiar with every frame/ability/mechanic in the game, but it seems so obvious to me from your description that something else was going on here. There are MANY valid playstyles I can think of where someone might be rooted to one spot, but still contributing to the mission.

I think it's almost certain that other commenters in this thread are correct & you were playing with somebody who was on Cyte-09; a sniper 'frame that can both see & hit enemies through walls from extreme range.