Since there is no lactation content in the game right now, why should there be the tag? Actually, it is very annoying when developers put tags for the content that doesn't exist at the moment, and maybe never will (since most games get abandoned early). Like those idiots who slap the corruption tag when all the actual corruption is starting wearing shorter skirts or brighter makeup.
The tags are correct and they show what really is in the current version of the game. Maybe there will be some lactation stuff in the future, maybe won't. Probably, the developers plan for it, but plans have a tendency do not materialize.