Loads of "translators" not trained in the original language have written Introductions where they state such things. That doesn't mean their defense of their enterprise holds water. There are a few translations out there by Armitage's forebears that ought to be seen purely as representative of their own poetry instead of an actual translation of a classic work.

Still, one has to give a pseudotranslator credit for admitting their method, unlike in famous cases like Stephen Mitchell or Coleman Barks where the edition doesn't even note that the supposed translator has no background in the field.

Armitage is pretty good at this. I've read his Green Knight and King Arthur stuff. I'll give him the benefit of the doubt until after I've read it.

I would argue than no one is really competent in a language that has been dead and unused for millennia.

The entire cultural context of that society and work is gone and we have but a few shards thereof.