Update, I just texted my friend and sent him a picture of the foam. He works in the management division of the power plant engineering department at an auto manufacture, and said that that high density rubberized foam acts to reduce sound and vibration created from engines that have a balance shaft assembly. Ok there you go!

 

Rodents in the Intake Manifold...
Sounds like a killer name for a garage band

 

OR

 

If it were me, I’d run away screaming. Too many horror stories from all marks about rodent damage to wiring. It may not show up today, but you cannot see everything. It’s your money of course, but my recommendation is to pass.

 

A little behind the scenes info about car dealerships. Most all of them contract with some sort of pest control company to frequently inspect the lot and buildings for rodents and other pests that can and do more than some think damage new cars. Most of the time the damage is repaired by the dealership. Those are part of doing business and generally unless it is a substantial amount to repair it is not covered by the dealership's independent insurance company or even reported. So yu you would never know if your MAZDA had a incident with rodents? And I can tell you firsthand many of those problems that take so much time to figure out why they happened when it is determined rodent or pest damage it is obvious it was there for a long time maybe years.
If it was only a nest for the rodent and no colored wired chew, then it is very unlikely there is any damage that may ghost the car in the future. Of course, I didn't inspect the car, so my responses are only my experience both working a dealership as well independent service shop.
I bet grimereaper (certified Mazda Technician) has some Mazda info about this as well. Maybe he will chime in with some thoughts?

 

@Callisto The photos were very helpful in seeing how that piece is constructed. Anyway, I went back and had a good look around with a flashlight and could see no indication of any rodent damage beyond the foam. I made an offer on it, so ball is in their court.

Thanks to everyone for your help/feedback.

 

Calli:
You found my old Big Daddy t-shirt collection???
That's a blast from the way back past.

 

Dude don't make me dig out my Odder Rod card collection LOL