I don't know if privett is where TSC gets their chicks. But last time I heard that is where Petrus gets their chicks. I've never heard of anyone having any trouble buying chicks there. Ours always have done well.
Privett is in NM. I read a detailed, angry blog that stated the problem was with TSC, not Privett, and explaining about vaccines. That's all I've had time to look at. BUT if Petrus uses Privett and there haven't been any problems, then maybe there's some truth to it. I'm not sure.
I guess the best, safest option is to get the chicks I want from wherever I find them and then vaccinate, or brace for losses. I can't remember the rules for vaccinating adult birds or if chicks would become carriers and infect my adults. I need to read and make notes again.