Pure speculation on my part, as I don't know anything about these tapes or who might have recorded them. But, I feel pretty confident that MSU, including Bond, Bell and any other involved boosters, gave the NCAA everything they had. I can't think of any reason someone would sit on these tapes, unless the tapes were recorded illegally or something.
The problem is the NCAA has suddenly decided to raise their evidentiary standard. In the past, when someone accused a school of breaking the rules, it seemed like it was up to the school to prove they were clean. Now they seem to be requiring a level of proof comparable to Court of Law. Perhaps they took this stance due to the stakes in the game, or maybe we have entered the era of a kindler, gentler NCAA.
Just because Cecil told MSU that UT and Auburn offered him money, that doesn't mean they actually offered him money. Perhaps he later told the NCAA that he was lying just to pressure MSU to pay.
Just because someone says Cam was in the room while a discussion was going on, that doesn't mean he was there unless you unmistakeably hear his voice.
Just because Megan Mullen says Cam told her "the money was too much", that doesn't make it true if Cam tells the NCAA a different story about their phone conversation.
I am patient. The NCAA is still investigating Auburn, and it appears they are not finding much. Perhaps the didn't pay for Cam after all. I would like the full story to come out, though, because I believe MSU did just about everything right this time, while Auburn should be embarrased about the situation, and realize how lucky they were to keep Cam on the field.