In this case, the text states that "Against Malaria Foundation can avert a year of human suffering from malaria for $39", which is just false. Going by the footnote, the $39 is the cost of extending a human life by one year. I'd recommend writing that in the main text, instead, if you want people to be able to disagree with your judgement calls.
While I agree that offsetting isn't the best thing to spend resources on, I don't like the framing of it being 'antithetical to EA'. Whether offsetting is a good idea or not is a good, object-level discussion to have. Whether it is aligned with or antithetical to EA brings in a lot more connotations, with little to gain: