I don't know if this could contribute to this theory:
The first thing I noticed while waking up on the citadel is that it first reminds you of the Collector Ship.
These tubes, piles of bodies, fluid pouring and general insectoid feeling to it. Even Anderson says this.

Then it strongly reminds you of the Shadow Broker ship all of a sudden. These electrical charged discs moving up and down, the footbridge and electricity receivers on the sides.
The footbridge on Shadow Broker Ship:

The footbridge on the Citadel:

The electrified discs on the Shadow Broker Ship

The electrified discs on the Citadel:

Ramps and receivers on the side on the Citadel:

Also, this I don't know but the room with Illusive Man and Anderson looks a bit like the room Illusive Man used to sit in, empty circular room with a holographic interface and a massive vision over a celestial body, when Citadel opens. The glowing ring on the floor is where Shepard used to stand on while talking to Illusive man, although in the Citadel version it's much bigger.

About the Shadow Broker thing: On Hagalaz the discs is to absorb electricity from the thunders constantly going on outside to keep the ship powered. Now, there's no thunder in space. Would the Citadel really need that kind of technology, seems out of place? That design seems unique to the Shadow Broker ship and I've never seen such thing on the Citadel. Something is not right here.
To me the environments in the last minutes of Mass Effect 3 seems to be "memories" from actual places Shepard has visited. What do you think?