Sorry this happened to you Andrew
There are a few things here
Until animals arrive safe and sound to a customer those animals are the breeder's responsibility.
As a breeder your job is to keep himself informed on temperatures which includes main hub through which the package will travel (usually between 11pm to 5 am), but you also need to keep up with various fedex alerts which are posted here
http://www.fedex.com/us/servicealerts/. Those alerts were even posted on sites like Reptiles2You, SYR and Reptiles Express which were all discouraging people from shipping last week. That job was not done it's also your job as a breeder to say NO to a customer when conditions are too risky. It's not the job of a customer to know all that.
I noticed that he shipped with 2 heat packs, while this can be done with a fairly large box and if done properly, doing so with a small box (which I would expect with hognose) could have easily killed those animals even if had not been any delay (but we will never know)
https://www.shipyourreptiles.com/en/...s#question-275
As a breeder if you offer live arrival guarantee you just offer live arrival guarantee and you do not put conditions afterward such as "well you should have take insurance" (which BTW was not available on SYR last week due to the issues Fedex was experiencing, the insurance would also have been void due to the use of 2 heat packs in a 12x9x6 box)
As a breeder if an animal is DOA you refund your customer or if you can you replace the animals with similar animals, a transaction and it's responsibility is not over until the customer is 100% satisfied.
As a breeder a DOA often means being out of pocket but that's a risk we all take when we offer live arrival guarantee (breeders have always offered live guarantee even before insurances were available)
There is no doubt he should issue a full refund.