I am not an expert but there are a few parasites that can transfer and freezing does kill a number but time and temp dependant most health places say -7ºC (19.4ºF) and 30 hours but things like virus are not nearly as likely to be killed at all. Some fungi. How many of those would effect a snake I don't know but to me I'd not risk it. I know my rat breeder tosses any natural unexplained deaths and only sells healthy animals she has euthanized.