I understand that this tech could be used for nefarious purposes, but this isn't world-ending tech. This is just hard to differentiate from human writing...
The choice to keep their "too powerful model" unreleased is more an attempt to stoke sensationalism out of journalists eager to report on "The AI too dangerous to release" than it is actually an earnest attempt at protecting society.
The dangerous rogue-AI is a Hollywood trope. We don't live in the Ghost In the Shell universe, we live in reality, and a text-generating algorithm isn't particularly dangerous when you think about it.