You can't block anyone. He just doesn't post a lot. Unless you have a custom algorithm like nostr:nprofile1qqsr7acdvhf6we9fch94qwhpy0nza36e3tgrtkpku25ppuu80f69kfqpzamhxue69uhhyetvv9ujumn0wd68ytnzv9hxgtcpz4mhxue69uhhyetvv9ujuerpd46hxtnfduhszrnhwden5te0dehhxtnvdakz7x08grv talked about at Nostr Valley then you will be unlikely to see certain things because of timing.