Instead of demanding proof, you could prove them wrong by providing an example of truths that are uncomfortable, but not considered bigoted.
0.999... = 1
Israel is doing a holocaust. Trump is all over the Epstein files. Epstein didn't kill himself. Half of American voters want a pedophile to be in charge.
Complex socio-economic problems usually lack fast, simple solutions.
Climate change that keep getting worse, rising political extremism, the wealth gap getting bigger and bigger, I can keep going but you get the point. You just have to open any news media once really.
HR approved "uncomfortable" truths.
As you can see from a sibling comment (turn on showdead), you're not allowed to post uncomfortable truths on HN. The non-dead sibling comments are quite comfortable truths that are pretending to be uncomfortable.