Greg - you're a great friend to have.
The perineul involvement isn't the best thing to have, but still all the mainline treatments should work. It does make it a slightly higher risk case. Even with that, I'd say he has time to look into all his options first.
You gave him all the good points. I would add that he should really talk to at least one RO before selecting treatment. The RT might deal with the margins better than surgery.
Hate to see people rush into treatments without getting all the options available. Hopefully you can talk him into a second opinion or two.
And tell him we're mostly friendly.