Why are people able to think more clearly after an epidural hematoma?

Unconnected. If a patient makes a complete recovery from an epidural hematoma, they should be the same as they were before the bleed. If recovery isn't complete, there will be some type of neurological impairment that is permanent. A person will not think better than they did as a result of an epidural hematoma. The two events are unconnected.