I am struck by your situation because my husband was diagnosed with prostate cancer recently and in very similar situation to yours -- even down to similar PSA scores and Gleason scores. While my husband has done extensive reading about what he wants to do (he has opted for surgery, in part due to his father doing something different and it not working well), I'm more concerned with his mental state going through this process than I am almost anything else. He is clearly VERY depressed and I don't know what to do about it.
Since you have done so much of the groundwork, I would suggest that you "keep him in the loop" with what you're reading and learning. I think he wants to forget he has prostate cancer at the moment, but you cannot let him. I know nothing about your situation, but you can always give an end date by which he needs to have made a decision -- or YOU will. Meanwhile, I would let him know how important it is to you that he take care of himself. This one seems to have worked -- a little with my husband.