Replying to them is giving them the attention they want. Rebuttals will just invite public arguments. Definitely deal with the problem, but do it quietly, in the background. Do not engage.
Engaging directly also let's them set the agenda. Deciding what info people need to neutralize the problem and publishing it let's you set an agenda.
Do keep in mind that if it becomes public debate, your most and least vociferous are both potential candidates as the author. Even someone very vociferous and seemingly on your side may actually be your troll doing all they can to keep the discussion going.
Do keep in mind that if it becomes public debate, your most and least vociferous are both potential candidates as the author. Even someone very vociferous and seemingly on your side may actually be your troll doing all they can to keep the discussion going.