The only way UVA would have any rights to dictate game time is if it is built into their contract with BYU and approved by ESPN, which is doubtful. This is one of the downsides of the current college TV contracts, the networks have the rights (within the limits of the contract) to determine game time and, to a limited extent, the date. I don't believe either BYU or UVA can stop ESPN from starting the game late Saturday night -- though there likely is some language in the BYU contract as to how late (say 10pm MT or later) the game can start.