He's (as usual) being deliberately obtuse.
Oxford United have pledge to fund and support the maintenance and improvement of the sports pitches at SB. This is conditional on the stadium development as sadly, we know that no stadium could very easily mean no club. But once planning permission has been agreed then this support for SB will be linked to the lease agreement with OCC and will therefore become the commitment that he is arguing for.
It's no different from agreeing to cut your neighbours lawn if you buy the house next to them. But you're not going to drive around with your lawn mower if the sale falls through and you end up living elsewhere, or in our case, become homeless.
The details are clear, no matter how much Middleton or others try to deny them.