"Heckler's Veto" is kind of close, though I'm not sure it perfectly fits the phenomenon you're talking about: https://en.wikipedia.org/wiki/Heckler%27s_veto ht

"Heckler's Veto" is kind of close, though I'm not sure it perfectly fits the phenomenon you're talking about: https://en.wikipedia.org/wiki/Heckler%27s_veto https://en.wikipedia.org/wiki/Heckler%27s_veto