The block function on Mastodon is absolutely terrible.
If you block someone, their comments will stay on your posts – meaning if someone makes a bigoted, hateful comment, your followers will all see it.
If someone else blocks you, their comments will also stay on your posts – meaning they can drive-by insult you, and there's no way for you to remove it.
Who thought up that system?
@redfern @SailorDisco The only way I know of having their comment not be disseminated by my instance is to suspend them. But I can only do that because I have my own instance of one.