The catalog prototype does not appear to have the two exposed wires featured in your pictures...
I think you spotted what Dean meant when he said that there's some "elements that suggest unfinished".
Dean's TurboLink is certainly is nicer than the one featured on
Computer Chronicles (Show #1043, "CD-ROM"):
16:53 - The mess of wires is totally unfortunate. The black cable is from the standard TurboPad. The TurboLink cable is thick and gray. The TurboLink would look awkward, but not nearly as messy if the DUO's controller was removed from view. The CD games aren't helping the situation, either.
You can see the PCB is green in the prototype above, but the gray cable and plastic housing looks nice.
J.B. uses the TurboLink to play Sherlock Holmes: Consulting Detective on a Mac.
18:19 Then he pulls out the adapter, slaps in Lords of Thunder (which he refers to as a "VHD" shooter... I've written about this elsewhere--it's a ridiculous term for "Vertical, Horizontal & Diagonal" scrolling in shoot-em-ups... TTi was desperate, but pathetic, with the marketing on this one. Thankfully, TTi never pushed the "VHD" angle anywhere else (to my knowledge).
19:50 Next, J.B. demos a game that was never released: "Thomas' Snowsuit" from Discis (Discus?) Books (they had published the title for Mac)
I've been meaning to collect all this TurboLink stuff on one page for my website, but I haven't gotten around to it (obviously).