Here is what you are missing, and this is coming from someone in the know how these things work. I worked as a Drum Major for the All American Marching Band and had to do similar things for our Ops Team for band and the university.
The University owns the equipment that is needed to provide A/C in the visitor's locker room and a request needs to be formally done via paperwork to the correct division within the University structure. That responsibility is left up to the visiting team because, you know, it's full of adults and not underage children. When that request never came in, Purdue did not provide anything they are not required. If you noticed, you didn't hear UM complaining about not getting the ice needed for their sidelines and that is because Purdue provided that as part of their responsibilities along with communication abilities from the sideline to the press box.
Again, in the statement you have provided that came from Purdue, they are to request the needed materials and the Purdue Athletic Department would notify them of the proper channels to obtain said A/C units. This has been going on since that building was built and this is literally the first time any team has come out and complained. Do you know why? Because other programs, including FCS programs like Indiana State has followed directions like any normal person would and obtained the needed equipment to ensure the safety of their own players. You know who else doesn't have air? Camp Randall, Northwestern, MSU, and any other damn stadium built in before the 1960's....you know, when A/C became readily available.