I vote for Johnston Atoll. It’s the perfect site; it’s already set up for him. From its Wikipedia article:
The isolated atoll has been under the control of the U.S. military since 1934. During that time, it was variously used as… a site for the storage and disposal of… Agent Orange.
The US has an island we can strand him on for the rest of his life.
There are plenty: https://en.m.wikipedia.org/wiki/Guano_Islands_Act
I vote for Johnston Atoll. It’s the perfect site; it’s already set up for him. From its Wikipedia article:
The amount of islands we’ve ruined to make gunpowder and strip of timber is fuckin crazy.