Beowulf translation is a whole academic field, the translation has been debated ad nauseum for 100s of years, Tolkien had his own translation and opinion, which differed from others. One additional scholar adding his own interpretation doesn't necessarily overturn anything. There is not enough detail in this article to know how compelling the case is or what the counter arguments would be.

The article references a forthcoming publication that I can't find a draft of. Here's an older publication on the topic by the same author: http://walkden.space/Walkden_2013_hwaet.pdf

Edit: Oh, the PF article is from 2013, so this must be the actual publication after all.

The paper (someone else linked it) makes a pretty strong argument with quite a bit of evidence.

It does seem quite likely that the translation that begins "What!" (with the exclamation mark being inserted by translators) was just an error by early translators who were over-indexing on Latin grammatical patterns which weren't at all common in Old English.

> There is not enough detail in this article to know how compelling the case is or what the counter arguments would be.

The only real way to make the case compelling would be to discover new Old English texts. So there is enough information; the case is not going to be compelling.