Your response is judgemental, incorrect and frankly unhelpful.
1) A host can respond to a review that has been posted by a guest.
2) It is possible to not be aware of mold until checking out. There are tenants that live in moldy rentals unaware of any mold.
3) With regard to their health, what you suspect has no merit. You are making a judgement.
There is no such thing as not being able to do anything. You have no idea based on their inquiry what losses they suffered. Your last statement makes you sound like a troll.