I used to work for this very airline. “Special pass” means buddy pass, and yes, there are strict dresscodes when it comes to flying on a buddy pass.
The woman that started the furor just doesn’t understand the issue. If someone laid it out, maybe she would, but it sounds like she has “the chip”, so she probably wouldn’t.
BTW, in our case it was Alaska Airlines.
It’s pretty standard policy. It is also quite reasonable.