The term does not necessarily mean jail alone.
commitment legal definition
2. An order, especially one from a court, directing that a person be taken to and placed in the care or custody of a hospital, mental health facility, prison, or similar institution.
In this context, the term committed means that these specific sexual offenders have been forced into longer prison sentences (an additional sentence above and beyond what the courts have decided prior to their conviction) or forced to stay involuntarily into other similar institutions.