If you attend a talk at a rationalist conference, please do not spontaneously interject unless the presenter has explicitly clarified that you are free to do so. Neither should you answer questions on behalf of the presenter during a Q&A portion. People come to talks to listen to the presenter, not a random person in the audience.
If you decide to do this anyways, you will usually not get audiovisual feedback from the other audience members that it was rude/cringeworthy for you to interject, even if internally they are desperate for you to stop doing it.
Takeaway: ask beginning of presentation what comments are allowed. If you're a presenter, specify it. You can then expect people to know that comments are unwelcome.
10Dean Valentine
I make the simpler request because often rationalists don't seem to be able to tell when this is (or at least tell when others can tell)