Underwear bomber "faces a maximum 20 years’ imprisonment"--is that all?

Am I missing something? He could be free at 43?

The Nigerian is accused of attempting to destroy an airliner and putting a destructive device on it. He faces a maximum 20 years’ imprisonment.

The 23-year-old suspect is the son of one of the richest men in Africa. Alhaji Uma Mutallab, 70, is a former chairman of First Bank and Nigeria’s ex-Federal Commissioner for Economic Development.