That is a truism that I did not find useful to call out. It's true that they can redefine words, even after millennia of usage, to suit their purposes. But, for example, defining that pi in legal contexts is exactly three serves only to make communication impractical, as if we are trying to talk to Humpty Dumpty in Alice & Wonderland whose words mean exactly what he wants them to and nothing else.

So it's true, they can create an arbitrary distinction. The problem with that is that it can be made to mean anything and, for that reason, is inherently meaningless.

I understand this to be the sort of vague law they, quite reasonably, normally attempt to avoid. I cannot see any reasonable justification for adopting that here, though I suppose that those in the patent bar have a monetary interest in saying otherwise.