There are tons of sites that have similar functionality and don't face any flaming issue. You don't need to essentially show the username who disliked the post . Just keep in mind every positive item needs an negative item in order to keep balance within things.
To keep things balanced maybe apply the "dislike" feature in the default product but leave it disabled here on these forums. Personally, I won't use the "dislike feature" but I can see why other people would want a balanced system in place.