Masters degrees, card carrying, secret-handshake knowing designer here. I remember when the notion of dark patterns was first discussed and differentiated from anti-patterns and I think this current discussion is quite ironic.
It's ironic because it is hinging on a narrowly constrained definition of "user interface" design - one that has been appropriated by web/app designers in recent years. UI goes well beyond what is IN the browser window. Discussion of user interfaces occurred before they were graphical user interfaces, well before they were web browsers. So for a discussion that hinged on the idea of the misappropriation of terms, this scores high for irony, IMHO.
SO, now that we're clear on the idea UI's can include many things, it's also clear that the URL and the items return based on the url requested absolutely fall under the notion of UI. And, this is most definitely an example of UI manipulation to create unexpected and negative results for the user to the benefit of the website.
Additionally I should point out, the whole notion of interaction design once meant something much broader than digital interfaces - as an easy example, look at Don Norman's early work and you'll see that interaction and interfaces go well beyond windowed interfaces or even digital interfaces.