However, besides the stylistics there is the main point of content. The Fonwegian ‘interposition’ (to borrow from Tolkien’s wording) is prefaced by:
Here I will interpose some material—which will save this paper from being too autobiographical.
And concluded by:
From here onwards you must forgive pure egotism. Further examples must be drawn solely from isolated private experience. My little man, with his interest in the device for expression of
syntword-relations, in syntactical devices, is too fleeting a glimpse to use.
To me, this conveys the message that the Fonwegian ‘interposition’ is non-autobiographical and non-egotistical. And the mention of the celebrated ‘little man’ implies that if Tolkien had managed to obtain more of the latter’s invented language, he could have provided us with a second bit of non-autobiographical, non-egotistical private language.
The stylistics, as Nelson suggests, might just be conveying an acceptable ‘conceit’ for Tolkien; but to my mind these framing passages, if not literally meant, would have been close to ‘deceit’ for a person of Tolkien’s character.