They wont produce a proven study about it being bad for rodents at all since there isnt one. Pine is safe to use mice and rats period.
I have rats kept on pine pellets as pets who are 4 years old. They never sneezed due to the pine but random sneezes as all animals do. So to say i dont care about my breeders or rats is baloney. I take care of them with the utmost respect due to what they were bred for i make sure their life is as comfortable as possible.