Thank you for your response. You're absolutely right, of course.
It's been a year and a half since I wrote this article so I've had ample opportunity to reflect on it.
I think my dad's difficulty was compounded by the fact that he lived in a developing country with very few resources. There are very few "third places" around, i.e. community spaces without a commercial agenda where people can socialise. Consequently, when his golf club closed, he didn't have many places to go - there was the park, of course, but that was increasingly inaccessible because it could only be reached by car, and public transport services are extremely limited.
Compounding this fact is that the society we live in is very close-knit. It takes month/years to make new friends - an investment in time and effort that's not easy for someone in their 70s to make.
I rack my brains to think of what he could have done, but after 18 months of thinking, I still haven't come closer to a decent answer.
Thanks again for this thought-provoking and compassionate comment.