I don't treat most of my water, but I definitely wouldn't want to drink out of Alamere Falls untreated. You're right that the direct watershed likely doesn't have much development in it. But Point Reyes sees so many thousands of hikers that I don't consider any of it to be wilderness. How many people go to Alamere Falls a year? A couple of hundred thousand? Many of them are just the general public, not LNT aware. It's areas like Point Reyes where one finds human turds in the middle of the trail and toilet paper blowing in the wind.
Now... If you get sick, you get sick. Likely no big deal. If you avoid hershey squirts and stomach pains in the first month, it'd be hard to attribute any future illness to Alamere Falls. I've got a little ailment right now and I have no idea whether it was due to drinking Sequoia NP water untreated two weeks ago.