The health department will deal with the restaurant, they will have an investigation and will determine if the owner of the restaurant has any expectation to have known about the distributor lacing their product. Single restaurants can’t go and inspect their distributor’s facilities, there is separate FDA oversight, so there generally is no reasonable expectation of a restaurant having oversight of the way a distributor is making their products. Restaurant owners choose distributors based on publicly available health and safety department information and sometimes because they have a good relationship with a rep from the company. it is a failing of governmental oversight that this distributor was able to mix a batch of personal-use laced ice cream in with ice cream set to be sent out, not on the restaurant owner who is using information from the government to make a determination if a distributor is trustworthy.