When he offered the female as free with the pastel, I would have asked for her history and where he got her. But I'm also aware that he's not a breeder, but an importer and re-seller.
All of the animals would have been quarantined in one room with me. None of them would have been introduced until after a 60 day quarantine, by which time the female would have had the explosive bowel movement and a fecal test run along with a vet visit.
The QT is where I think you made your mistake in your eagerness to start breeding. If someone sells me a breedable weight female, I don't assume that means that she is ready to breed without first going through QT with the other animals I brought in. Especially when I know that they import animals and imported animals very often can carry internal parasites if not treated.
If I purchased from Ben Siegel, who also imports and re-sells, I'd be QTing and fecal testing any animal from him as well. He's got a great reputation as an importer and re-seller.
When I purchase from Michael Cole, I know he works with imported animals. I QT and fecal test animals from him.
The mistake that Josh made was that he didn't give full disclosure on the female which unfortunately had a questionable background and had internal parasites.
You've said that you're satisfied with the resolution that you and Josh have come to.
Again - as I said before - I think there are mistakes made by both sides. I thought that you both had come to an amicable resolution.