It’s a little aside from your point, but good feedback is not only useful for emotionally managing the rejection—it’s also incredibly valuable information! Consider especially that someone who is applying for a job at your organization may well apply for jobs at other organizations. Telling them what is good or bad with their application will help them improve that process, and make them more likely to find something that is the right fit for them. It could be vital in helping them understand what they need to do to position themselves to be more useful to the community, or at least it could save the time and effort of them applying for more jobs that have the same requirements you did, that they didn’t meet—and save the time and effort of the hiring team there rejecting them.
A unique characteristic of EA hiring is that it’s often good for your goals to help candidates who didn’t succeed at your process succeed at something else nearby. I often think we don’t realize how significantly this shifts our incentives in cases like these.
One aspect of the framing here that annoyed me, both in the OP and in some of the comments: the problem is not controversial beliefs, it is exclusionary beliefs. Here are some controversial beliefs that I think would pose absolutely no problem at this event or any other:
The many-worlds interpretation of quantum mechanics.
Virus gain-of-function research creates more risk than it prevents.
Nuclear energy is a necessary part of the transition away from fossil fuels.
The problem with racism and transphobia is not that people disagree about them! The problem is that these beliefs, in their content on the object level, hurt people and exclude people from the discussion.
Let’s avoid using “controversial” as a euphemism for “toxic and exclusionary”. Let’s celebrate the debate and discussion of all controversies that threaten no-one and exclude no-one. Suggesting any of that is at stake is totally unnecessary.