I don't see how the Operative is taking over the Engineer's role here.
If an Engineer doesn't place a turret, the Operative isn't going to be able to build one.
I'll agree with you if and when it turns out that the Engineer gets less than the normal amount of points for the turret's damage/kills, because that would be unfair and annoying. I'm fairly confident that won't happen, because it would go against everything the devs want for Brink. I've posted my suggestion for both players to get full XP for the kills already, but that's what I think would be fair.
Also, if a player wants to grief a teammate, this isn't going to be the best way to do it. It relies on your target remaining as an Engineer, AND continuing to rely on turrets that you can reach.
Because he is taking over there turret. Operatives have there own role to fulfill. They have objectives, and abilities what are useful to there team like hacking enemy turrets, revealing enemy positions, infiltrating withing them and cause chaos. There is no reason for them to be sitting around taking control of an engineers turret. As mention below wouldn't 3 guns be better than 2? Why sit somewhere safe and control that Eng turret when you could be out there with that Eng helping him while his turret lays down suppression fire?
I don't see how the Operative is taking over the Engineer's role here.
I"...or are a griefer."
This is just another example of classes interacting and supporting each other. Operatives can spot mines, and Engineers can then disarm them. Engineers can set turrets, and Operatives can then control them for greater effectiveness. Like, for example, if the Operative wanted to help his Engi pal hold down an area. It's all about teamwork.
Yes, the potential for griefing is certainly there, but I submit that a griefer would grief with or without this ability.
I get your point but wouldn't 3 guns be better then 2? Why have the operative take control of your turret when it could shoot on its own leaving another person with a gun to shoot to help the Eng hold down the area. Thats teamwork not taking control the turret then your leaving that engineer short handed.
I agree a griefer will grief with or without this ability but this certainly make it easier for them to do so. This bring another question up I havent seen anyhting mentioned about a kick system being in place. Wonder if they will have a VTK or "x" amount of TK auto kick or something in place to regulate the sabotaging of the team.