It seemed obvious to me that "if it doesn't directly affect you" was an implied caveat throughout. He set it up in the introduction as "when it has nothing to do with you." This line seems to sum it up: "If it’s not directly affecting you, your life, or your happiness, it’s none of your business." If something is directly affecting you, it is your business.
In general that's a good rule and I agree with most of what he said. However, sometimes people do things and make choices that may not affect a given person directly, but do have an effect on a community, the environment, or some other larger group or entity. That's when you start getting into a gray area. I've seen a number of huge fights when Person A objects to something Person B is doing because it has a negative effect on a larger group, while Person B insists it doesn't matter because it doesn't affect Person A directly. I find myself almost always on the side of Person A in those situations.
I agree with you in a larger sense, but I really didn't see much on that list that would potentially cause harm to a larger community. Eating/exercising choices, clothing choices, and tattoos clearly should be individual choices and therefore respected (or at least silently tolerated). More come down to gossip: medical information, successes and failures, and habits are all things we should avoid gossiping about when we know the person involved would object to the gossip. Looked at a different way I suppose there can be an argument that the behaviors themselves can be detrimental to a community (a serial moocher, for example) but I think it's still valid to say that approaching the individual in question - once - is better than gossiping about him/her to other people.
A bunch dealt with re
lationships, sex, romance, and marriage - again, the actual decisions involved can be harmful (marrying an abusive person, for example) but that still doesn't give anyone else the right to usurp the personal decision to get involved in a rel
ationship - and to have the freedom to define what they want that rel
ationship to be. Three more boiled down to "don't stick your nose in other people's finances," which I absolutely agree with - if those finances don't directly involve you, you have no right to naysay financial decisions.
That just leaves religion, friends, and parenting - three things the world will never agree on. There will always be people who take "safety trumps etiquette" to extremes based on unreasonable interpretations of "unsafe." If you (generic you) have no concrete reason for why an individual should choose your interpretation of what's safe over their own, I don't really blame that individual for wanting to avoid the topic.
All in all, I do agree that you can interpret the list in a way that allows some exceptions ("What if she lets her son drink bleach?"), but if you look at it as a list of "Please don't gossip about me doing X" I think it's a pretty good list.