The district court in that case ignored the infringer's argument, but why give the infringer any ammunition by using the term "prior art" in the disclosure context? Certainly we want inventors to provide a list of any references they're aware of which may be relevant – but an attorney should be involved in the determination of what is or is not prior art.
The post Keep Your Story Straight: Five Important Patent Terms from the blog IP Law for Startups agrees with me, noting that:
“Prior Art” is a legal conclusion that should be made by an attorney, a judge, or the USPTO. An inventor runs the danger of making an “admission” that a reference is Prior Art – when in fact it is not.