In Lennon v. Metropolitan Life Ins. Co, the 6th Circuit had joined that chorus of courts that have denied health insurance or life insurance benefits to someone who drives drunk and hurts or kills themselves. The court held that such "accidents" are not accidents at all when you drive drunk and get in a crash.
The plan administrator was not wrong to deny benefits. Obviously, you should never drive while intoxicated. Besides all those other good reasons like you might get arrested, hurt someone or face increased insurance rates, you might also find that none of your hospital bills are paid and, if you die as a result of your foolishness, your family may be denied benefits.