That's like saying the cops can use heat-sensors to look at houses, because thats just electromagnetic signal and you can render it however you want. No invasion of privacy there right?
I would argue that since the NYT is willfully delivering you the content of an article and merely instructing your browser to conceal it, that's a far cry from "trying to 'lock' their door." If someone was distributing their username/password or an authorized cookie, or using a server-side exploit to access content, then I think that would constitute a breach of ethics if not law.
Basically, my point is that once the NYT willfully transmits data to your computer, you should be able to manipulate it any way you wish, obviously barring any sort of commercial use or redistribution that violates copyright laws. Anyway, it's not that hard to protect data from certain users and make it available to others. That's a design pattern as old as multi-user computer systems/networks.