Hi@Homecarer, welcome to the forum. It does sound like your son is thinking about the present rather than looking ahead too much.
I have a (sort of) similar issue with my 80 year old mother. She refuses to register with 'My Aged Care' because she says she's fine at the moment. That's debatable but that's another issue. I've had some tentative success by pointing out if she registers now, and gets in their system, she doesn't need to use any services or funding, but it's there right away if something happens or changes and she needs it... she wouldn't need to go through the application and waiting times if something suddenly came up where she needed or wanted it. It seemed to lower her resistance slightly... i'm still working on it but I just thought a similar tact may help you convince your son.
Best of luck with it.