The clever radar thingy needs thermal signature to detect the ship though. So if the 3rd person gunner view depends on the radar sensor data, it shouldn't be able to spot any targets where there are no temperature differences. So yeah, it could spot a ship on the other side of the asteroid but not the other side of the asteroid and not even the ship if it was running silent.
Also in general a lot of people are saying that it's possible to make a photogrammetric reconstruction of the scene even now in 2017 and use that as an argument that it should be easily possible over thousand years later in ED. Well yeah, it should but if photogrammetry is used, you need to triangulate your observations like this:
https://wiki.hexagongeospatial.com/index.php?title=Photogrammetric_Solutions
For the solution to be robust the so called base to height ratio must be high enough or the accuracy of the measurement degrades. What this means is that the sensors (cameras) used to capture the observations need to be wide enough apart in relation to the distance to the observed target. So basically with a ship like Corvette this could be entirely possible because the ship is very long and thus would have a long baseline. On the other hand the accuracy should degrade for targets that are forward or rear because the ship is much narrower compared to the length of the ship. Similarly with smaller ships this should result in much lower quality 3rd person view quality. Also as stated by other posters, this wouldn't solve the occlusion problems so if the 3rd person view was generated from camera data from near the ship, the offset camera position should show a lot of blind spots.
Personally though none of that matters... ED takes place over a thousand years into the future and surely there will be some technology to observe the surroundings in much better detail than what we can do now so that's not why I'm against that gunner view. What bother me however is that the gunner view seems so disconnected from other ED gameplay. It also makes silent running pretty obsolete if SR ships are shown in the gunner view. It simply doesn't look nearly as fun to me than the holographic representations we were shown in concept artwork or the other combat aspect already in the game.
As stated numerous times in this thread, there are a lot of explanations why 3rd person view is totally possible with the technology that should be available in ED, just like autopilot, aimbot and such would be. Still we don't have autopilot, why? Because this is a game and if everything was automated there would be nothing left to play. This gunner view is taking the game in that direction and seems disconnected from otherwise immersive and excellent basic mechanics we have in the game.
Finally an answer to the "don't use it then" crowd. I haven't heard of an option to block everyone who uses gunner view from affecting BGS. Though they already said REP will not be given from multicrew sessions, maybe they could also make the sessions to not affect influence either. If that's going to be implemented then I can continue playing the game without using the 3rd person cam. However I don't see FD firing up their own galaxy for people who want to use 3rd person cam so I can't simply choose not to use it but we'll see...