Yeah, I don't disagree with that so long as the particular context is included when being passed off as normal in specific conditions. It was not mentioned that the professor stated this was for mass production and the comment was provided in a context that invalidated what they said. In context, without the edit, the professor's advice is immaterial to the discussion and only serves to spread misinformation on proper hygienic practices.

But to the overall point, this is why you don't listen to random people on the Internet! Sometimes you get told facts that are only true for very specific edge cases that are bandied about as general advice with the weight of 'i have a degree' as confidence even though the advice is objectively wrong in the provided context.