Same thing happened with the original test screening for HALLOWEEN (2018). A guy notorious for loving the original sequel from 1981, went around to blogs, etc. and told them that the reaction to the film was extremely poor, and that the film was in extreme trouble. Whereas in fact, I know first hand, it actually got very strong reactions. The only negative was a certain sub plot, and that the original ending was anti climatic.
Test screenings can go either way but it's frustrating when one person tries to speak for everyone with their extreme bias.