Mary Beard is a great scholar, and I don't want to be misunderstood as saying otherwise. There is more than just language proficiency to successful academic life, after all, and it is by no means the most important thing. For many reasons, knowing a language well is less valuable in academia than than knowing something else about the people who used the language, or having something worthwhile to say about texts written in it. The Czech writer Jan Kresadlo was at home enough in Homeric Greek that he was able to write a brilliantly hilarious Science Fiction Epic in it. But his facility with the language did not mean that he knew the first thing about Ancient Ionian land tenure practices.
But, that said, I think I agree with a couple of the authors points: She is brave to admit her lack of fluency and may have overstated how hard it is to learn.
Also worth reading is this, linked from the original blog: there's a conversation amongst latinists/classicists and they don't all agree with this polemic: