No tiles. No flaps. It's not an aerodynamic vehicle, so it's not destined for use on Earth, nor will it return to Earth. It's hugely reinforced.
The only thing that occurs to me that makes any sense at all is that they're playing with moving the structural reinforcement from the interior to the exterior. It serves two purposes. The first is to reclaim a small amount of tank volume. The second is
MMOD. A bit of extra mass where it'll do more good. It should make a good
Whipple shield - if it hits the stringer first. Who knows, maybe the next step is to install a thin skin on top of the stringers.
The speculative reason that they don't create a Starship from scratch this way is that they don't have the tooling to do it and that they can't stack a ring with external stringers.
I can't imagine them laboriously removing the internal stiffener system, but maybe they'll do that. They're doing
this, after all.
And now another idea occurred, which is that they're going to need this reinforcement for installation of the HLS landing engines. I would think that a more ideal location would be just under the cargo bulkhead, but moving them away from a possible crew area might be desirable (yes, despite Dragon having a bunch of thrusters practically touching the crew). If true, then they'll install a bunch of thrusters and do some static fires.
Any other crazy speculation?