Even though I don't know the specifics of your father's situation, I would urge you and him not to despair.
My husband (53) also has stage 4 prostate cancer spread to bones, lungs etc. etc. But at 1,946 his base PSA was much higher than your father's, which often indicates that the cancer has spread further. We were also told that it's 'terminal', and I suppose that the word 'terminal' makes most people think that you're going to die soon. That's surely how we understood 'terminal'. But with PCa, 'terminal' can mean anything, and I know of many people who have been terminal for 3-4 years now, and are still going strong. We decided to say 'screw the statistics', let's assume we're going to be the lucky ones who will beat the monster for at least 7 years.
His oncologist wrote a letter that my husband is fit to work, and he passed a medical for a job in a post-conflict country. In fact, he feels better than last year because the PCa is under control for now. His PSA has dropped to 0.17 in less than 4 months, which is great.