Hadeedak wrote...
The oily shadows and reverb go away. If the indoctrination was continuing, you'd expect the other 'dream' effects to carry on, since if it's more 'intense' it should be stronger.
MY personal opinion (and I swear, this is like the third time I've said it, not that it's your fault), is that they stop attempting to indoctrinate Shepard after the attempt with metaphorical TIM fails.
They are pressed for time (remember they are in the middle of a battle, they don't really want casualties, nor do they want to decimate the species of the galaxy because it would be counterintuitive to their established ME2 MO - to create new Reapers using us). Their attempt to indoctrinate Shepard has failed, so they show Shepard what he wants to see - the citadel arms open and the crucible docks.
Could Shepard be nice for once and just die believing that he had won? No, of course not! A little part of his subconscious has realised that he is
not finished yet and in the dream
this is manifested as Admiral Hackett's voice commanding Shepard to make the crucible work. At this point I think the Reapers saw that he was about to break free from the illusion, and once he realizes that he is still alive in London in the Rubble there is no telling what trouble he could cause (seriously, he's already mucked up their plans three times now, and they've already tried killing him once and it didn't stop him, they're not going to assume they've won yet).
They need Shepard to believe that he has won. They use the "Catalyst" and the chamber to give Shepard the illusion of choice (and it is presented realistically to him - a low EMS shepard would expect to have less options that result in more destruction because they understand they are reasonably less prepared. A Shepard with High EMS might not accept not being able to destroy the reapers, which is why the "choice" is offered).
In the end, the choices mean nothing because all they want Shepard to do is
stop fighting.