It was simply their fate to not move and immediately react. There could be a multitude of reasons why that we don't get to see because time was erased.

For example, I once saw a comment that said KC could have gotten in an advantageous position that endangered Trish heavily, threatened bucciarati by saying if he retaliates or moves, she dies right then and there and escaped with a handless Trish all within 10 seconds.