I was referring to not communicating clearly as the bad habit. By simply assuming a meaning instead of calling it out, the person who initially spoke ambiguously gets no feedback that their statement was unclear.

And the principle of charity or charitable interpretation requires interpreting a speaker's statements in the most rational way possible and, in the case of any argument, considering its best, strongest possible interpretation. It means that if a statement could be read in an irrational way or in a rational way, you choose the latter. So if for example I said "sheep are white" you could interpret that to be the obviously false claim that 100% of sheep are white with no exceptions, or as the much more reasonable statement that sheep are typically white, where the principle of charity would be assuming the second interpretation. It has nothing to do with bending over backwards to make a statement palatable.

The hacker news guideline you are thinking of is "Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize."