Such behavior infringes on the opportunity of others to decide whether or not they want to hear the speech in question.

is this just supposition or can you show where this actually happened?

The moment there was an alternate conference in the same town on the same weekend announced by the objectors it became about a balance of resources and attendees. Those who are organizing, presenting, and attending Moonconf have every reason to badmouth anyone associated with LambdaConf.

Here's one of the early objectors citing a presenter who has openly and thoughtfully struggled with attending LambdaConf: https://twitter.com/swannodette/status/714851217512513536

Here's an early Storify story of reactions to allowing Yarvin to speak - you will find that the most vocal objectors have continued to bash and badmouth anyone associated with LambdaConf: https://storify.com/adngyipa/lambdaconf-debate-in-tweets

This comment (plus many others on Twitter that you can find by searching "lambdaconf sponsors") suggests that all sponsors but one pulled out due to pressure.

https://twitter.com/fatneckbeardguy/status/71358678287339520...

So I put some tweets in another message, but they weren't exactly the ones I was referring to; like I said, search is difficult on a phone. But I didn't want to make it seem like I was misconstruing what was said, so I wanted to post some clearer ones as well:

"@47deg Hi, are you still going to sponsor LambdaConf if they give a platform to someone who thinks blacks are suited for slavery?" - https://twitter.com/ekrubnivek/status/713501535515226113

"@andrewfnewman @adrienneleigh So, the racist organizers of lambdaconf selected his talk knowing who they would get? Smart move, clearly!" - https://twitter.com/extempore2/status/714502151884505088

"If you've spoken at LambdaConf: have you repudiated its organizers for making the choice to include bigots and exclude marginalized people?" - https://twitter.com/fatneckbeardguy/status/71280436894525030...

FWIW, extempore2 was making the opposite point - he's been one of the most vocal in criticizing the boycotters.

Ah, sorry, I did not realize that. One of twitter's many endearing features is how easy it is to take tweets out of context. I'd edit my post to remove it, but I can't.

Twitter search is terrible, especially on a phone, but here is some:

https://mobile.twitter.com/antifuchs/status/7128837259948236...

https://mobile.twitter.com/antifuchs/status/7128835537977057...