Tomorrow, the message will be yesterday's by-gone, and given what I know about grz, he is not so overly-sensitive as to be as offended as some might get over a simple colourful expression.
In the meantime, I see the statement that one mans food is another man's poison is without any factual basis.
I'd like to see just one example where a food substance was nourishing to one man, and poisonous to another. The whole notion is preposterous ! Outrageous !