The author's comparison of the fonts actually argues against them being of the claimed lineage. Consider the many differences between the Taylor, Taylor & Hobson machine’s fonts and the Gorton machine’s fonts. If Gorton had a license to use the Hobson machine designs, which they did, they could have simply copied the TT&H fonts verbatim. But they clearly did not. Why not? I think it's likely that they simply preferred a different design, one closer to the letterforms that were more commonly used by draftsmen in the American market. In other words, the Gorton reference design was not the TT&H font design.
At least, that's my best guess based on the evidence presented.
> Each of these reappearances made small changes to the shapes of some letters. Leroy’s ampersand was a departure from Gorton’s. Others softened the middle of the digit 3, and Wrico got rid of its distinctive shape altogether. Sometimes the tail of the Q got straightened, the other times K cleaned up. Punctuation – commas, quotes, question marks – was almost always redone. But even without hunting down the proof confirming the purchase of a Gorton’s pantograph or a Leroy template set as a starting point, the lineage of its lines was obvious. (The remixes riffed off of Gorton Condensed or the normal, squareish edition… and at times both. The extended version – not that popular to begin with – was often skipped.)