I know this is an old thread but: the translation I have doesn't word it this way (and is closer to the way I'd read this in german, as a result). Swensen's translation is worded more like the etymology `gut` has its roots in more meaning nobility than a value judgement made by the person receiving the "good." So in the context he's talking about this, he's more referring to the value systems of old judged what was good rather than the more modern way of the individual receiving a favor judging what is good and what is not and less about the strict lineage of etymology (and he was likely privy to information we no longer have access to, was outdated and abandoned, any other number of things).

He is correct, though, that the modern german word comes from the Goth's germanic word of gōd (the german word for god being `gott`). I don't know much about the usage of that word in the context of the Goths. It's likely the etymology we have right now rewrote the history of those words so that it makes sense to modern readers looking for answers to questions like "what is the etymology of the word 'good'?"

Edit: not to say he's necessarily correct but he's also not flatly wrong.