Re: Any lawyers in?
"The cable _isn't_ directional, and you could prove that at the network layer"
Ah, but the devil is in the detail. What they're saying in the full blurb is that they test each cable individually at point of manufacturer and identify the best way round to plug it in. They naturally work both ways, but they'll figure out which way round encourages a finer flow of unicorn p1ss through the cable. Your definition of "finer" may vary.
They can probably demonstrate that two of the twisted pairs are of marginally better quality than the other two pairs, and thus the two better ones should be used for the tx between NAS and router/DAC/unicorn-stable.
All nonsense of course, but we're down the rabbit hole here anyway....