the ESRB only rates the content of the game, they do not rate the conduct of the developer themselves. It's a totally different thing to include suggestive content in your game than it is to be suggestive in your announcements about the game. Red text is not a 'character' in warframe per se, it is a direct communication between the developer and the player, and that kind of communication is both unrated, and far more important to conduct professionally.