This is spot on. Spigen has the resources to bet on the wrong horse, so to speak. It was ready to go if need be, and it needed be. Other manufacturers either don’t want to take that risk or were just straight up unsure.Spigen may indeed have had some Apple guidance, but my thought was this:
On release day Spigen had no cases with a CC button. But they knew something about the upcoming button. To quote Caudabe: "we anticipated the new capacitive touch button early on". So it was not a secret that it was coming - even Caudabe knew "early on".
So I think that Spigen made a conscious decision, as soon as they knew about the button, that they would be poised to figure it out and go to production ASAP. Given the scale of their sales, Spigen probably was able to get their Chinese manufacturer to "hold the presses," so to speak. Caudabe, being relatively small scale, probably didn't have that option.
Just my speculation...
Spigen may have got it wrong, and in the event it did, is in a position to eat the cost. A fair bit of resource goes into developing cases, and especially when producing in scale. The *safest* option was to release cases without the button, like the majority have done.
We saw a similar thing last year with the Action Button…