There is a different between the "strongest" interpretation of a comment and the "best possible light".
For example, if somebody tells me "Angersock, you can go happily fuck yourself", I'm not going to expect them to be wishing me a rousing and cheerful round of masturbation--that is the "best possible light", but not the "strongest interpretation".
Properly handled, assuming the worst of a comment, articulating the argument you think is being made, and then rebutting it, is far better than just assuming the best--provided it's done civilly, of course.
You're responding to a pretty weak interpretation of what we're talking about here. :) The point is to address the strongest plausible interpretation of what another is saying. It's pretty well-established what the Principle of Charity means [1]. (By the way, you can see from [2] that there's an ongoing discussion about formalizing it for HN.)
I don't think it's a stretch, mutatis mutandis, to take even a comment like "go fuck yourself" charitably. It could, indeed probably mostly does, mean "I'm angry about something unrelated."
Since "you can happily go fuck yourself" is not in fact an argument, the principle of charity does not demand that you interpret it as anything more than a rude interjection. At its strongest, it would require you to assume that the commenter was legitimately upset and deeply invested in the argument, which would perhaps keep you from responding in kind.
> At its strongest, it would require you to assume that the commenter was legitimately upset and deeply invested in the argument
I don't think even at its strongest the PoC would require you to assume that the commenter was legitimately upset, only that the commenter was intending to express that they were upset.
The PoC only applies to interpreting what the intended message is, not to conclusions about its justification as would be necessary to support the interpretation that the commenter was legitimately upset.
I can't help but suggest that your pretty nitpicky distinction between "interpret[ing] in the best possible light" and "rebutting the argument you think is being made" is, perhaps, not interpreting the argument for the guideline in the best possible light.
For example, if somebody tells me "Angersock, you can go happily fuck yourself", I'm not going to expect them to be wishing me a rousing and cheerful round of masturbation--that is the "best possible light", but not the "strongest interpretation".
Properly handled, assuming the worst of a comment, articulating the argument you think is being made, and then rebutting it, is far better than just assuming the best--provided it's done civilly, of course.