Agree with the control of content theories. To a lesser extent, but still probably worth a few bucks, is a desire to sell off and/or develop land he's acquired through all these buy-ups. To wit:

"We believe that MID's real estate business and Magna Entertainment are a natural fit due to MEC's highly attractive underlying real estate assets...MEC's assets include under-utilized excess lands in some of the premier real estate markets in the United States. They are prime locations for premium retail, entertainment, and/or residential development." Brian Tobin, CEO of MI Developments, as quoted in a bloodhorse.com article earlier this year.

MID, by the way, owns a big chunk of MEC equity, and they hemorrhaged money last year, posting a big fourth quarter loss.