It's generally a bad idea to tell someone their choice of struggle is a waste of time, and that they should do something More Important. By way of Orac:
... there will always be issues more important or more impactful than what any of us does, with rare exceptions. Pointing to them and using them to denigrate someone’s efforts as pointless, which, make no mistake, is what Hogan [sic] comes across as doing, is not constructive. Rather, it is a very old strategy to denigrate that which you consider unimportant.
I came across Horgan's piece by way of Peter Woit's blog, and I am not happy to report that Woit, whom I normally consider wise, wrote approvingly of Horgan's porridge of nonsense. I suspect it's a case of Woit seeing some things he agreed with on face value and then letting Horgan do the rest of the thinking for him (a phenomenon I'm all too familiar with on my own). The article is depressing for a lot of reasons, but mostly because its central argument boils down to wagging a finger at some population and saying: Why aren't you doing what I like?
One of the minor, but still annoying, ways I encounter this on my own is when I tell people my day job involves writing about computers, but I write fiction on my own. More than once I've had people look over my stuff and say — not unkindly, I guess, just unthinkingly — "Why don't you write a techno-thriller? You know a lot about that sort of thing!" My usual reply is that I don't want to, because I find other topics more interesting for my fiction. I've suspected more than a few times the reason I get asked this question is because the person is thinking This stuff you're writing doesn't interest me, why don't you do something that does? but doesn't have the nerve to come out and say it. (Or maybe they pity me because they think I could make more money by writing a Tom Clancy clone.)
The whole "you should be doing something else" cult, from what I can tell, stems from two things. One is the need to feel superior, which can have many manifestations. In this case, it's coupled with ingredient #2, the inability (or the refusal) to understand that everyone needs to have their own priorities. They need to be able to pick their own battles to fight, and while some of those battles are going to seem incomprehensibly trivial to others, they're going to mean the world to the person fighting them. Maybe the reason I'm not as interested in stopping war as I am in stopping vaccine hysteria (to use an example cited above) is because someone I loved and was close to, like, say, my child, suffered or died because of the latter rather than the former. It's stupid to infer that because I have chosen a different hill to die on, I therefore think you're fighting a stupid battle.
There is another manifestation of this argument, one I call the Argument From Existential Urgency. The AFEU goes something like this: "My" problem is more urgent than "your" problem, because if we don't fix "my" problem first, it's going to kill all of us, and "your" problems will be moot. This is actually not a bad argument in the abstract: if we don't do something about the rise in global temperatures, for instance, a lot of other problems will be moot because a great many of us will drown, or fry, or both. But it's still unwise to position it as a zero-sum argument, because then it stops becoming one of the ways each of us can decide how best to spend our individual and collective resources, and starts becoming a tool for shaming, demonizing, and attacking others.
If someone else refuses to help you save the world, tip your hat and go look for someone else. There's more fish in the ocean than you might think.
(Addendum: Horgan stamps his feet some more. "I accomplished what I set out to do, to provoke a debate about skepticism." That's like saying someone who lights a cigarette at a gas pump is just conducting a vapor test.)