Minecraft does not ban users for profanity. The list of ban offenses is currently:
Hate speech, sexual content and soliciting improper contact, real life threats, exposing the personal information of others, posting links to malicious software, impersonating staff, cheating/exploits (this includes anything that would negatively affect another person’s gameplay experience), general commercial spamming
Profanity is considered the responsibility of specific server moderators since it's a low-level offense that's virtually impossible to police in a game like Minecraft. They're trying to avoid the notoriety recently obtained by Roblox for being a place for adults to exploit children.
If my own experience years ago is any indication, this would create so many ban options it’s not funny. 10 year olds love pretending to be more than they are.
Oof. They're kids. Cursing here and there is not the end of the world.