Why retired Hamilton cutters went to navies rather than NGOs

Could nongovernmental organizations buy retired Hamilton-class cutters for maritime protection work?

Not realistically. Governments were acquiring the ships, while their large crews made them less suitable for NGOs than lower-manning offshore patrol vessels.

Hamilton-class ships are durable and useful, but their crewing requirement remains substantial. Smaller navies can accept that burden in return for long-range presence and patrol capability. Most nongovernmental organizations cannot assemble or sustain a crew of that size. Lower-manning offshore patrol vessels fit those operators more readily.