I am wrong in thinking that ethernet is opto-isolated? If that assumption is correct, I assume this negates any electrical effects that a switch could have on interference (ignoring UTP differential pairs and assuming that this is never an issue anyway)?

And I assume this switch isn't doing some absolutely insane decoding of some common unencrypted audio protocols to 'improve' audio in any way.

As everyone else has already said... what an insane money-grabbing audiophile-abusing product :D