Right. "Rational" is perfectly fine to use when it refers to the set of behaviors and strategies for making choices that best advance goals and forming beliefs that are true-- typically characterized by fields like heuristics and biases literature, Bayesian epistemology, akrasia and executive functioning etc. It is also acceptable as one of the less unfortunate ways of referring to Less Wrong projects and individuals/ people inspired by the above concept of rationality, in general, at a meta-level. What it is not suitable for is as a substitute for words like "optimal", "best", "ideal", "true", "good" or "moral" on object-level, narrow-domain questions. While "rational" might be denotationally synonymous with these words it carries an additional connotation which suggests the post would have something to do with the aforementioned conception of rationality as understood by Less Wrong. A post about the best way to cook a chicken should not be called "Rational Poultry Cooking". I'd add to your target list "Exterminating life is rational" as I think that post should simply be called "...is moral" or "...maximizes utility".