This kind of word policing is even less OK. It's not "gross" to make a comment about something you see and have opinions about, especially for a public figure. You're not shedding light on any subject, either, all you're doing is being offended-on-behalf of someone else; the world's got enough of that and it doesn't seem to be making any positive difference at all.
I am not "policing" anything. I have no power to arrest someone or censor someone for being an asshole online. I expressed an opinion about the kind of community I'd like to be a part of. Also, it seems like you're doing what you're criticizing me for. I don't think the world's got enough of minding one's own damned business regarding people's health, body, and appearance, and that having more of it would make a positive difference. This conversation is about the science of fasting, not whether Jack Dorsey looks thin.
Sure, but only in a meta-sense to curb the proliferation of the technique. I'd liken it to nuking would-be nuclear powers to prevent further problems.
And maybe, _just maybe_, Jack Dorsey should eat a sandwich.
So, when you wrote this, did the idea of using nuclear weapons preemptively seem like an obviously good idea, to you?
There is a fascinating wikipedia article about this you should skim when you get the chance: https://en.wikipedia.org/wiki/Tu_quoque
You don't know anything about the guy's health. He may actually be sick, wholly unrelated to his diet. He could be dealing with an eating disorder (which may be related to his diet, but millions of people have fasted regularly without having an eating disorder...there are lots of ways people cover for eating disorders). And, maybe he's in great health and your beliefs about what "healthy" looks like are wrong ("put some meat on your bones" is not great health advice for most people, but it's a common refrain).
I don't really know anything about what he's said about diet or fasting. But, I know that bringing his appearance and health into it are not shedding light on the subject, they're just conflating appearance with health and well-being in ways that aren't useful.