As David (Purgatory) said, it would be helpful if you could post a few more stats. However, here are some preliminary thoughts:
1. Most docs do not advise watching wating with a Gleason 7 cancer.
2. You said "oncologist". Is this a prostate oncologist you are visiting, a urologist, a radiation oncologist???
3. Depending on you hubby's stats, and given his age, brachytherapy (seeds) might be a good option. A uro-doc, as a surgeon, may not be to keen on this approach. For this reason you should make sure your husband sees a radiation oncologist and a prostate oncologist so that you have a good feel for all of the treatment options.
4. I also don't get your doc saying might as well do a two-for-one surgery. That doesn't feel right to me.