Because it's a classic flamewar topic which leads away from the specifics of this story and towards generic hostilities; and because taking a stronger interpretation of the comment would have made the question unnecessary—i.e. scott_s is probably just as aware as the rest of us that fish are animals and their flesh is in that sense meat, and therefore he was probably just not using the word 'meat' in that sense.

scott_s replied in an evenhanded way, but many (maybe most) commenters in his position would have taken the question as hostile and responded in kind.