The [friends] think it's distracting or that it's wrong because it's not Gortogh's actual thoughts but the narrator who is not a character (or should not be at least) in the story.
Damon's friends, and indeed, his wife, are complaining about his use in narration of an expression that he uses in everyday speech:
n feet long if it was an inch!
which he then goes on to echo and repeat (one repetitions and two echos in three paragraphs; see yesterday's post for details).
They complain that they hear Damon's voice narrating, and that this intrudes on the point of view that is presented, weakly, in the passage, the POV being that of the goblin (see yesterday), Gortogh.
Setting character points of view aside for a moment; who or what is the narrator?
I contend that the narrator is not the author. The author is a real person, who sits in front of a screen for much of the day, spending anything from 50% to 95% of his time "researching" (surfing the 'net), and anything from 50% to 95% of the remaining time cleaning his fingernails and staring out of he window. The remaining time is spent tapping away at the keyboard with 20% to 100% of his fingers. (I use 90%).
The narrator is voice, chosen by the author, in which to tell the story. Sometimes, though not always, the narrator is also a character in the story. In Sherlock Holmes, Watson tells the story, and Conan Doyle uses Watson's voice to do this, however he takes care to write as Watson would write, not as Watson speaks. Fairytales are traditionally told in the "Mother Goose" voice; a benevolent parent who is all knowing and gentle, even when dealing with violence and death. Tolkein uses this voice for The Hobbit, but in LOTR he uses a more worldly voice, though no less authoritative. Chandler popularized the use of vernacular in the first person; but notice that while both Spade and Marlowe are voluble and opinionated in their narration, they are sparing and occasionally monosyllabic when speaking. Narration is not about how people talk; it is about how they narrate.
It is one of the great arts of the author to choose, establish and maintain the narrator's voice. Narration is not the same register as normal speech nor as normal writing (essay or letter writing, f'rinstance). Nor is narration character nor point of view dependent. The author makes choices about what the narrator knows and what the narrator chooses to reveal. The author makes choices about how the narrator communicates to the reader. I describe the narrator as a voice. The narrator can't be called a person - as the author seldom if ever narrates as himself. The narrator isn't a character, even if he is presented as such; Watson is himself narrating, not living, the events. Spade reacts in his narration in ways that he does not react in his action, and in any case he doesn't always tell you everything. This is the author's choice.
The author is one of the people. The author's choice of narrator is one of the voices.
The other person is the reader. Reading, the reader "hears" the narrator's voice. Even if the author is excessively skilled or gifted, however, the voice the reader "hears" narrating will not be identical to the one that the author hears while writing. The reader brings to the book all his personal baggage, all his reading history, all his listening history; this colors the narrator's voice that he "hears"*.
The reader is the second person. The reader's narrator is the second voice.
Characters are subjects, objects, agents or agonists of the story; they are ciphers rather than people. Indeed, in French, we describe a convincing character not as 'realistic' as we might in English, but as vraisemblable - literally "able to seem true". This trueseeming is the test of a good character.
Narration presents Points of View (POV). A POV is a narrator's choice, and is used to control the flow of information to the reader, for a particular effect. Strong POV has two main purposes: to limit the amount of information available to the reader to what the character knows, and: to bring the reader into closer sympathy** with the character. Weak POV serves to keep the reader's focus on a specific character without limiting it.
Sometimes strong POV feels like the character is telling the story even when the narrator employs the third person.
The POV known as "omniscient narrator" can pick and choose between strong and weak POV's, depending on the requirements of the narrative.
The issue Damon encountered with his beta readers is a special case. They know him. As a result they can't help hearing his voice when reading his work. When his narrator uses as distinctive idiom that Damon likes to use in everyday speech, they find it intrusive because Damon's voice (the author) interferes with their personal narrator (reader's narrator). This won't happen to readers who don't know Damon. That is not to say that it is not a good indication that the author should, perhaps, revisit the passage in question (or ask his editor to!), and see if the narrator's voice needs to be made more consistent.
My initial reaction (see yesterday) is that an interlude is a good opportunity for the author to play and experiment. I may change my mind depending on how closely the events of this section interlock with the events of the story proper.
* I'm using scare quotes here because many, possibly most readers, don't actually hear a voice in their heads while reading, at least not consciously, unless the author has made a specific effort to make that happen. However it is something like hearing, for which English doesn't seem to have a word.
** In lit.crit., sympathy does not imply liking or identifying with a character, only that you recognize what the character feels.