It's just an appeal to authority. There are plenty of silent majorities that are real, but often the arguments that built those silent majorities are sound on their own and are much better to argue with, so there is no reason to point out a silent majority.
Like, not being a flat earther is a silent majority, because 99% of people don't even think, talk or discuss such ideas, but you don't need to rely on a silent majority to debunk it.
"Wow, don't take things so seriously!"