You answered whether GEC would allow it with "why not?" as a rhetorical question. But that's why I prefaced my query by observing uniqueness of the fluidity of the Tidioute Cutlery barlow compared to the rest of the GEC line. Considering this, it'd be more natural to as "why" (not "why not?") would the #15 barlow don BOTH Tidioute AND Northfield trim without changing the TC stamp on the bolster?
I feel I have as good an understanding as anyone (meaning a general idea with nothing concrete) as to how the TC barlow came to be (partnership/agreement between Waynorth and GEC), so I'm not seeking clarification on that back story. Rather, I'm observing that this is a departure from what GEC does with 99 percent of their offerings. Most every model is produced in two primary lines: Tidioute and Northfield. If they were to follow their model with the #15 barlow, we'd have an initial release #15 Tidioutes (with a TC bolster) and crescent nicks...followed by a release of their Northfield counterparts (a #15 barlow with a NF bolster and longpull + swedges!). But GEC has departed from this when it came to their #15 barlow (almost certainly because of their partnership with Waynorth). But in light of this, the question is not "why not," but rather...."wow, interesting...an anomaly" (in other words, "why?" when they basically never do this on any other model (I realize there are some one-off exceptions)).
I mean, if we take the vast majority of their catalog as an indication, GEC may say they don't want Northfields having standard nail nicks, as a brand/product line thing. Case in point: canvas micarta, which they do not want on Northfields moving forward.
But if we take the #15 barlow as an indication, they may be fine with "Tidioute trim" on a knife with a "Northfield" mark.
So, I don't think it's a "why not" question. But I do think it's an interesting question....for GEC and for knifeswapper.
I was fortunate enough to get two of these 2018 #77 barlows. They are amazing and they even represent the blade configuration I was hoping for (and suggested....along with many others) back in 2017. Love the longpull. Love the 2-blade clip/coping barlow. But seeing my modest collection of #77 barlows with these 2 new additions, I can't help but wonder what's next

, even as I enjoy what's in front of me. And my FAVORITE #15 barlow is a single clip point with a crescent nail nick.
And so....I begin to dream.....of what could be....on the #77 frame.