Greg, sorry for the experience and glad you're OK. Not gonna start and argument. You were right, the guy w/ the boat was wrong.
I understand how winding, two-lane roads around a lake are a problem. I see it every week, as I'm the guy in a pickup truck pulling the boat. The roads are quiet, wooded, peaceful, and I understand the attraction for biking. On the other hand, those same roads are the only access to the lake for boaters. The bicyclers have a choice. I don't.
Quite frequently I'm stuck behind a herd of bicyclers for miles because there is no safe place to pass. Miles. 10mph for miles. It is frustrating. While I creep along, I think about the extra taxes I pay for those roads via boat taxes, trailer license, trailer taxes, truck license, truck taxes, boat gas and truck gas. It is frustrating.
I don't know the answer. The guy who passed you on a curve was wrong. It's frustrating.