Much depends on how big the blinds and antes were relative to the stacks. If you're 20bb deep his shoving in the SB every time is probably -EV. Eventually you're going to have a premium hand and take all of his chips. If you're fairly short stacked, his shoving nearly any two cards here is probably +EV. Depending on the stack sizes and the antes, your shove with KT might have been good too, not sure.

Post some hands over in the MTT forum and people will help you out.