Exactly.
I try to avoid using the word “subject” in such cases. As i understand it, in Buddhism (and in science, or at least I think it should be in science!) all “principles” or “natural laws” are mere descriptions (upādāya paññatti). Thus they are generalizations inferred from experience, but they do not “exist” in any sense, and hence have no power to “subject” anything.
So the better way to phrase it would be, “Is it appropriate to describe Nibbana in such terms?”
To which the answer is, sure, why not? Nibbana is described as not-self in the late canonical Parivara, which shows that the early Theravada tradition, at least, had no problem using it in that way. I don’t think it’s philosophically problematic: clearly, Nibbana doesn’t fulfill the normal requirements for something to be a “self”.
I think it’s more just a matter of context; these specific phrases were dealing with a different topic (insight meditation), so it’s not a good idea to use them to support an argument on the nature of Nibbana.