The two-item drop last month was surprising for many reasons (including pricing), but I think the J53TS-GT might have been largely responsible.
Given that it was released just last Fall with identical specs, and lingering on the site then also, I think that the 're-release' was/is just a second attempt by acr to sell all the J53's that might have been returned last Fall - even having Lenny re-do a photoshoot with the olive 3A-1 to convince us otherwise. The J47A-WS could have very well been slated for release at another time (SS18?), but was expedited to accompany the J53 're-release' to avoid a somber solo re-stock of the J53TS-GT.
3RD-ARM releases have always been sporadic/unannounced as far back as I could remember, so there isn't anything new there. All said, I'm not entirely convinced that the quiet release model is really what is playing out here (though I really hope you are right).