I cannot remember if it could be set up so that the beneficiary could not sell the payments ahead for a lump sum. If you can, this is something you want to do-lock down the thing so he doesn't decide to cash out and take a great honeymoon to the Bahamas.
I hope so. I totally understand modhatter's fear that someone will target his son. Perhaps modhatter may be able to set him up in a caregiving home while he can that may provide some protection from predators. My MIL is in such a home. 60 years is a long time, though.
I would suggest doing some intensive research on such caregiver arrangements ASAP. That is how we found the group home for my MIL. Find support groups, charities and government agencies and talk to people. Certainly there must be people who have the same problem? I wonder if the Salvation Army would take basic oversight? If the instrument had a pay-on-death to the overseer, it might persuade such an organization to do the job without immediate payments, patiently waiting for his eventual death. Just brainstorming here.
You have my best wishes, mod.