I don't see what the big deal is -it's an innocuous metaphor. First time I heard the chicken and pig story I thought it was funny and it made the point very well. Being upset or at all bothered by this kind of thing is a waste of time any energy. Yes, words mean things and there are some words and terminology in this world we should be more careful with. Chicken, pig, and ScrumMaster are not those kinds of words. Lighten up.