Tim, you cracked me up!!!
I'm leaning towards holding the processor liable for their death, although like other posters, I have had Cornish crosses drop dead while I was looking at them.
In Dallas, I found that I could only grow them out between October and February; any other months are too hot. I had one crop of birds that were maturing in March (with temps already over 80) that wouldn't get up and walk 3 feet to the water; they would get up, walk to the food when I put it out, and then stay next to the feeders until the next time I brought the food out. I ended up having to bring the water to them! I have stopped raising Cornish birds at all, for the reasons everybody listed: they're almost mutant. They have been bred to grow so big, so fast, that their common sense and natural chicken behavior is gone. Even the times when I restricted feed, their internal organs were much fattier, and some had enlarged hearts, leg bones that weren't straight, and abnormal-looking gizzards. When I want meat birds now, I raise RIRs or Rangers, or get the slow-growing meat birds from Ideal.
If they had died at home and you came upon them within an hour of their death, I probably would have gone ahead and processed them. If they had been sitting in the heat and been dead for the whole two hours, I don't think I would have, even if they had died at home (although I would have fed their meat to the dogs, after cooking it).
I have been hunting and processing the meat since I was a little girl. I also processed my own chickens. I can tell you from experience that it only takes about 20 minutes after death for the quality of meat to decline. If a carcass is not completely bled out and cooled down within those 20 minutes (more emphasis on the bled out), there is a distinctly different taste to the meat.
I'm sure that was traumatic; I'm sorry you had to go through it.