Places outside the Ivy League do have traditions, after all.
True. Absolutely, undeniably true.
But "Trad" isn't short for "traditional." "Trad" has a much narrower meaning.
"Trad" describes the clothing and overall look that Harris and other like-minded persons have favored for decades--the kinds of things that they would buy at J Press, The Andover Shop, and similar merchants.
All "Trad" clothing is traditional, but not all traditional clothing is "Trad."
Harris coined the word "Trad" in an attempt to describe not just any kind of traditional clothes, but an identifiable sub-type of traditional clothes: the clothes that he likes, whether they originated in England or the American South or New Haven, Connecticut. The boundaries of that subset are admittedly fuzzy, because Harris' definition of "Trad" is sketchy rather than exhaustive, but that doesn't mean that anything that's traditional can be lumped into his subset.
I have nothing against dividing the huge category of "Traditional Clothes" into sub-categories. However, since Harris has already assigned the word "Trad" to one sub-category, I think we should find another word for the other sub-categories and leave his word alone.
Why not simply use "Traditional"? Thus, there would be "Pacific Northwest Traditional," "Rocky Mountain Traditional," "Southern California Surfer Traditional," and so on.
If we are going to affix the "Trad" label to any subset of traditional clothes, then all right--after all, it's just stuff we wear, so no big deal. But at least, as we are doing so, we should be aware of two things:
1. Slapping "Trad" onto a bunch of sub-categories causes us to stray far afield from the garments that Harris had in mind when he started this shebang, thereby corrupting the word that he coined; and
2. We are not making any sense:
(a) "Trad" means, roughly, the Ivy-League-inspired (but not necessarily Ivy League) clothing that Harris prefers. Harris' description of "Trad," while subject to some interpretation, cannot reasonably be said to even approach, say, the garments that have long been sported by ranchers in the Rocky Mountains or the surfers of Southern California. Therefore:
(b) There can be no such thing, for instance, as "Rocky Mountain Trad" or "Pacific Northwest Trad" because a sub-category cannot be both Trad and not-Trad at the same time. (But there sure can be "Rocky Mountain Traditional" and so forth.) If it's Rocky Mountain, then it cannot be Trad. If it's Trad, then it cannot be Rocky Mountain.
Individual garments can be both "traditional" and "Trad"--desert boots, khakis, wheat jeans, and flannel shirts, to name a few. Jeans and cowboy hats, while traditional in some contexts, are never "Trad."
If you wish to use "Trad" as if it were just a shortened version of "Traditional," feel free. Doing that, however, will muddy the waters. And make Harris weep.