"Jack knives" is a very broad category. It seems like standard usage to me.
Of course, but in "GEC speak" and given the precedent of 54s that came before this one their 2-blade models with both blades opening from the same end have always been "big jacks"
I don't get the Weasel naming of the new 48 either. It's no different (pattern or feature wise) than other single blade 48 they've made in the past, so therefore calling it something else at this point is puzzling. At least it doesn't have the word weasel in a gaudy or garish blade etch. Are they done with blade etches, for the most part, on standard production pieces? I actually like some of the etches they used, but I know I'm probably in the minority. Now that I think on it a bit a nicely styled weasel etch might've been nice.
Regardless, GEC does keep things interesting, no doubt.