They are currently in a “Damned if you do and damned if you don’t” situation.
If they continued to use the spillway to prevent rising water from topping and breaching the earthen dam, erosion around the spillway will cause Oroville Dam to breach at the spillway, but if they shut down the spillway, water will top and breach the earthen dam.
The proper course of action is to evacuate downstream populations and hope the rain stops long enough for them to shut down the spillway and repair it.
They evacuated 192,000 people down stream earlier this week, and now those people (most of them are back home).