If we're going to keep running with this thanksgiving comparison, they're not asking for the relative not be invited. They're having a party the day after, a party to which the crazy relative was never invited, and decided to cancel that.
You make it sound like they randomly woke up one day and decided, for no particular reason whatsoever, to not hold an event they had already put enormous effort into planning and scheduling. They are cancelling their event in an attempt to pressure LambdaConf into bowing to their political demands.
> If we're going to keep running with this thanksgiving comparison, they're not asking for the relative not be invited. They're having a party the day after, a party to which the crazy relative was never invited, and decided to cancel that.
How would that behavior make any sense, though, if you're a person who doesn't want to disrupt the Thanksgiving dinner? They already didn't invite the crazy relative to their own party; what more do they want?
Back to the thanksgiving dinner thing: they don't really want anything other than to make it clear what they're having an issue with. But they're not asking for anything, just saying: this is incompatible with my values, I'm taking myself out.
What else do you want them to do? Compromise their values? Who are you to demand that of them? Or demand the crazy relative be booted, making the whole thing horrible for the host? They took the only reasonable action given their values: take themselves out of the equation, and explain why. Anything else would have been either childish or cowardly (again, given their core values, which you might disagree with or not feel quite as strongly about).
If their values are "we cannot interact in a professional manner with people who hold views we dislike," their values are bad and they should compromise them. If we can't get along with those with whom we disagree when necessary to accomplish unrelated things, we might as well disband this country and start arming up for civil war, because that's where this road ends.
Maybe you could. Maybe, if someone had consistently argued that you and your family were of an inferior race and should bow to their will as is your ordained place in the universe, you could shrug it off and say, "let's agree to disagree and get on with things".
I'd guess this has never happened to you though. I'd guess you can have this position because this is not your safety and your rights that are in danger. It's always so much easier to consider hatred acceptable when you're not its target.
In a professional environment we all have to compromise. You can't expect to only run into people who share your values and/or validate and approve your life style, or even what you feel is your identity.
I'm fine with working with people whose don't share my values. I wouldn't be with someone who very publicly and very repeatedly advocated me and my family being enslaved. If you are, good for you! just don't expect everybody to share your obvious strength of character and forgiving nature.