Specifically, if a letter asserts that there's no sign humans have caused climate change, then they don't publish it, instead hoping that some other letter may contain factual information.
This strikes me as reasonable enough; the usual comparison to creationism applies. I would limit it somewhat - if a LTE quoted one of the very few peer-reviewed, skeptical abstracts, then that's not complete nonsense. Whether an outlier opinion deserves such a prominent placement is the next question and probably depends on the letter and context.
My anecdotal sense is that the false equivalence of ten and even five years ago in the mainstream media over climate science has changed, and the LA Times is one example.