The short time frame for the turnaround is kind of surprising for the conference just to start ignoring them, although it is similar to the school in Baltimore that people are starting to compare to IMG.
The story reminds somewhat of the old Kankakee Valley Conference, which lost football when St. Anne gave it up after 1978, and sent the other 5 football schools scurrying for years (Herscher, Momence, Bishop McNamara, Peotone, Clifton Central). The conference ended up disbanding in the late 80's to get rid of Mac...the rest of the members formed the River Valley Conference with a bylaw that no private members can join. It was the final straw sending Mac to the Catholic League. But from the non-football schools, it made sense - since several of them hadn't beaten Mac in basketball or other sports for eons (Manteno's basketball losing streak was back to the 60's I believe; heck, Zinanni might have been a student at Mac the last time the Panthers beat the Irish in hoops). Logically, why stay in a conference where the larger private school is hammering you with kids from your town who are going there because you don't have football?
Ironically, when Manteno, Peotone & Herscher left the RVC for the I-8 in all sports in 2006, the RVC started taking private schools. Crete Illinois Lutheran has been a member since, and Kankakee Grace Christian joins in the fall...But I don't picture Mac being interested in the slightest...