I stand with the anonymous parent. This is a slipper slope. Banning people from technical conferences just because they have other opinions does not seem right to me. Ok racism is bad, but what if tomorrow people will be offended by other things like ideology (this conference accepts only republican speakers), or religion (this conference welcome only Christians speakers and all Muslims are banned) . As long as an ideology is not acted upon, I feel wrong to ban it . Banning ideas or ideology, even if morally wrong, often produce the opposite result. Moreover if somebody is invited to talk about technical content that is per-se neutral, and this person is not there to pursue his/her personal agenda, it is about loosing a important contribution to science for no reason. What is this code of professionalism would have banned the scientist that put that small dishwasher on a comet a couple of years ago just because he had a pinup t-shirt in his closet ? Slippery slop. We are scientist, and we talk science during a technical conference. Let's keep it this way.