The cures wouldn't cause mass suffering. If they just announced: Pharma has had the cures for all your woes! The stock would tank, they'd go bankrupt and people would riot. The entire world would suffer because Pharma supplies the entire world. The take down needs to happen behind the scene so it doesn't affect the economy. After it's cleaned up and prices drop, then you can reveal what was done to clean it up.
The cures are going to come out anyway before they try to cover it up. Forcing the release and quietly arresting them through resignations is the better option.