A working prototype would be considered "reduction to practice", which is less important under the AIA First to File rules. This particular application has a priority date of March 15, 2013, which is one day before those new rules went into affect (this is probably not a coincidence). Therefore, the application would be subject to reduction to practice implications under the pre-AIA rules (Section 2138). That section is lengthy, but the most relevant parts are copied below.
From MPEP Chapter 2100, Section 2138: Pre-AIA 35 U.S.C. 102(g):
[Editor Note: This MPEP section has limited applicability to applications subject to examination under the first inventor to file
(FITF) provisions of the AIA as set forth in 35 U.S.C. 100 (note). See
MPEP § 2159 et seq. to determine whether an application is subject to
examination under the FITF provisions, MPEP § 2159.03 for the
conditions under which this section applies to an AIA application, and
MPEP § 2150 et seq. for examination of applications subject to those
Pre-AIA 35 U.S.C. 102 Conditions for patentability; novelty and loss of right to patent.
A person shall be entitled to a patent unless -
(g)(1) during the course of an interference conducted under section 135 or section 291, another inventor involved therein
establishes, to the extent permitted in section 104, that before such
person’s invention thereof the invention was made by such other
inventor and not abandoned, suppressed, or concealed, or (2) before
such person’s invention thereof, the invention was made in this
country by another inventor who had not abandoned, suppressed, or
concealed it. In determining priority of invention under this
subsection, there shall be considered not only the respective dates of
conception and reduction to practice of the invention, but also the
reasonable diligence of one who was first to conceive and last to
reduce to practice, from a time prior to conception by the other.
Pre-AIA 35 U.S.C. 102(g) issues such as conception, reduction to
practice and diligence, while more commonly applied to interference
matters, also arise in other contexts.
Pre-AIA 35 U.S.C. 102(g) may form the basis for an ex parte
rejection if: (1) the subject matter at issue has been actually
reduced to practice by another before the applicant’s invention; and
(2) there has been no abandonment, suppression or concealment.
To qualify as prior art under pre-AIA 35 U.S.C. 102(g), however,
there must be evidence that the subject matter was actually reduced to
practice, in that conception alone is not sufficient. While the filing
of an application for patent is a constructive reduction to practice,
the filing of an application does not in itself provide the evidence
necessary to show an actual reduction to practice of any of the
subject matter disclosed in the application as is necessary to provide
the basis for an ex parte rejection under pre-AIA 35 U.S.C.
102(g). Thus, absent evidence showing an actual reduction to
practice (which is generally not available during ex parte
examination), the disclosure of a United States patent application
publication or patent falls under pre-AIA 35 U.S.C. 102(e) and
not under pre-AIA 35 U.S.C. 102(g). The disclosure in a
reference United States patent does not fall under pre-AIA 35 U.S.C.
102(g) but under pre-AIA 35 U.S.C. 102(e).