There's a difference between isolated incidents where an individual says something offensive, where it can be hard to decide on the right repercussions if any at all, and then there's recurring offenders which should be dealt with much more harshly. If someone has demonstrated that they will do or say harmful things on more than one occasion, a zero tolerance policy makes sense to me.
I shouldn't ever have to think "I'm glad idiots x y and z aren't coming to lan" because lan is where this community's members engage with each other the most, and if there's any feeling of apprehension about individuals being a part of the community at it's most inclusive time, why would we accept that elsewhere?
I'm not ecstatic about wanting certain people to be excluded but there's just a limit to how much shitty behavior I can witness in a person before I stop giving them the time of day.