IIRC from an article about the switch on one of the local news sites, the "official" reason athletics gave to Peoria Charter for ending the relationship and not renewing was DIA wanted fewer breakdowns (believe DIA gave a specific number) and Peoria Charter told them that it was impossible just do the nature of the buses. Anyone who's spent time on coach buses knows that breakdowns are just a fact of life, and it's not a question of if they will break down, but rather when they will. This is particularly true on long trips, ones that mainly affect non-revenue sports since basketball and football fly to road games. I think when the band and cheerleaders bused down to Tampa for the Reliaquest Bowl, they had at least 3 separate, unrelated breakdowns. Considering there were 9 buses in that group, only 3 breakdowns over a 2000-mile round trip is pretty good as far as coach buses go.
The point is, that's a terrible reason to not renew the contract Peoria Charter, and there has to be a different, internal reason to end a 25-year relationship out of nowhere like the DIA did. Whether that reason is as petty as it's been suggested as being mad they'd take a contract with Purdue or something more legitimate that hasn't been mentioned publically. It could easily be as simple as this Iowa company just undercut Peoria Charter, and being a public institution, they the DIA had to go with them.