The narrative I've heard that makes the most sense to me is that the RNC realized that Schiff really could beat their boy in Connecticut, Simmons. Terrified at the thought of a Senatorial Ron Paul, they sent out an SOS to all the Connecticut big-shots, looking for somebody that could do a "big, big favor", and Vince McMahon's wife answered the call. The McMahons are not millionaires, they are billionaires. That $24M was pocket change and will be repaid a hundred-fold, one way or the other.
At this point, it doesn't matter whether Linda McMahon wins or loses. Mission Accomplished: Schiff has been neutralized.