Personally, I consider all of those "false bugs" as gems. As I said in my OP, these are all indicators of where I can make my product more usable. Perhaps that unrelated link should not be placed quite so close to the submit button, for example. Of course, this is all theory on my part since I can't see what that tester compalined about. And, perhaps, we decide that the impact is low enough to warrant not fixing. But at least we know it's there - an informed risk vs an uninformed risk.
I agree - exposure should be part of risk calculation. But you only need to educate those who may become exposed. For example, the last time I was on a pig farm was ... lemme see... never! But the last time I was on a beach that was reachable by sharks was ... January, 2004. (I'm landlocked where I live, in the middle of the Canadian prairies, with many a farm within a small distance.) So learning about the risks from sharks is way more useful than learning about the risks of pigs. Exposure is critical, and is what Bruce ignores in your quote. There are probably also newsletters and newspapers and the like dedicated to farmers. There may even be government-funded booklets and the like which farmers would look at that the rest of us don't. So who is to say that there is more effort expended for one than the other? It's just that, to save money from being needlessly wasted, the effort is targetted to those who are at higher risk. Lots of people go to the oceans for vacation, so shark education is useful in the general public, but very few are exposed face-to-face with a pig. You, me, and Bruce wouldn't see the pig-risk documents. But those who need to are much more likely to have seen it.