The key reason is perhaps this, buried deep in the text: "We have also received feedback from OpenAI, which asked us to implement changes". Given the volume of prompts that AI Dungeon throws at GPT-3 in the course of a game, it's easy to conclude that Latitude has a real sweetheart deal on the usual pricing, and that they basically have to follow orders from their benefactors.
Whatever may be said of the robocensor they've thrown together - and early anecdotal reports are, it is painfully crude, both oversensitive and underspecific - how they've handled communicating the change is extraordinarily naive. Not for the first time, either: Latitude has form on suddenly imposing major service constraints in a peremptory, underhanded fashion that infuriates their customers. Repeating past PR mistakes, and now doubling down by complaining about "misinformation" and throwing shade onto others, is starting to look like a pattern.