I know this conference is probably not using this particular blocklist, but why should a conference 1) use a blocklist and 2) block people just for being of particular political view?
1) To ensure that known trolls/predators do not show up.
2) Probably because consent can be enforced this way much easier than it can be created in a real discourse. Especially in Germany it is frowned up by leftists to even talk with people from the right-wing spectrum.
I get (1), but (2) makes me wonder whether we learned anything from history at all.
You keep them out of the loop to some degree and would check against that list during registration. It apparently catches some at least, I am told.
I also know of 2 larger conferences in Europe where accounts were monitored and if activity indicates the person is present, they were removed from the venue by security.
1) Some political views correspond strongly with problematic behaviour that a conference would rather not deal with.
2) Virtue signaling for PR purposes.