That's definitely not typical road salt rust, where the rear end (rear axle area) rusts out first. Beach rust I guess.
The transmission crossmember appears to be structurally compromised. It has bubbles forming, which means you have layers of rust and the metal has lost some portion of it's cross-section to rust. The area in front of the passenger side front body mount also looks pretty bad (the AC drip line discharges in that area), as does the frame where the front bump stops contact it. The rust is super-bubbly in both of those spots.
If there is someway that GX can be unloaded/returned, I'd go that route. Probably depends on your state laws....here in MO they are sold "as-is" and you'd have limited recourse unless the seller was downright fraudulent, but I'm not sure if Florida has better buyer protections.
If you can't unload it I'd inspect it in more detail, including the inside of the frame (with an inspection camera) and see how bad it is, especially where the AC drip line discharges (the frame can rust from the inside out there). Maybe it's just the outside (again, beach rust that I'm not used to) and maybe it is salvageable.
Long story short, didn't get a good look at the rust until post deal (100%) on me. there is general surface rust on the underside of the car; I assume typical FL car stuff. However, some significant rust at the front. I didn't get a picture, but the very front of the frame (???) where it connect to the bumper is pretty rusty too.
