That shock tower is minimal, mine was from Ohio and daily driven from my understanding. The rear sunroof drains badly damaged the body and the shock tower where the fingers meet the frame rusted. Then ultimately the rear subframe to frame rotted away. Hidden things would be brake lines also. All in all, that is a very beautiful car and is extremely nice for 20 years in the north.
The sunroof drains would have no effect on the shock tower fingers, the front hoses drain into the front of the rockers under the fender, the rails under the fingers rust because Ford in their infinite wisdom sprayed a blob of expansion foam in there, directly above the hole where the wheel liner clips in and the whole thing turns into a sponge in a humid climate. The sunroofs effect on rust is debatable in general, of all the rotted out Chicago area MN12s I've looked at model year has more to do with the severity than the presence of a sunroof.
People from the North travel to the South to buy cars, not the other way around! I grew up in the rust belt. Even if you park the car inside, they get a little rust on them out of sympathy.
I just noticed the shock tower rust on that car, that is not a good sign. It is amazing how far water travels into the engine compartment. You don't realize it unless it contains salt.
Humid climates can wreak havoc too because of all the fabric sound deadener and foam Ford slathered these cars with, my friend's SC came from Florida and it has significant floorpan rust from the inside out, salt will only really start playing havoc after the steel is already compromised. If I wanted a truly rust free car I'd look west, not south.
The shock tower rust isn't a big deal. Look inside your wheelwell, the seam between the panels is clearly exposed to the elements, the wheel liner ends just below it, and the panel gaps are all over the place, allowing for plenty of splash intrusion. The good news is it's mostly just surface rust on the top extending from the bare spotwelded unpainted metal inside the seam, not rust through.