Perhaps so, but I think it is enough in the vicinity of the chilling effect line that it is worth discussing and being concerned about. I say this specifically

Perhaps so, but I think it is enough in the vicinity of the chilling effect line that it is worth discussing and being concerned about. I say this specifically because it was a professional conference and such conferences are important for earning a living. If private organizations vital to earning a living voluntarily censor people for their political opinions, that is equivalent to denying careers to those people, and that is a substantial chilling effect. If it's one conference, occasionally, then sure it's a minor effect; but look at the Hollywood Red Scare and you'll see it can become a major one. Personally I'm even more uncomfortable with forcing private organizations to ignore participant politics than I am with chilling effects, but let's not deny the chilling effect. A culture which denies professional opportunities on the basis of personal politics is lacking tolerance and diversity where it really matters: for ideas, not just skin shades and accents. Then again, China took the opposite model and seems to be doing fine. So YMMV.