The new rule since COVID, is that each team will start with a runner on 2b in extra innings. The runner is determined by who made the last out for each team in the previous inning.
So, Kirk made the last out for the Jays in the 9th, he had to go to 2b. 99% of the time you would pinch run for him. The Jays had already used everyone on their bench except Brandon Belt. He is also pretty slow but might also have some injury concerns.
In addition, if you PR for Kirk then you lose your DH. Jansen was DHng. So Jansen would go to catcher and we would have to use a pitcher to hit if the game was still tied.
In the past we had some pitchers who were more athletic.. However, the most likely option was Kikuchi and he is a SP and was not warmed up... To have an SP with our lack of depth get hurt on the base paths would be a huge hit to the long term team prospects.
So, I guess the coaching staff made the decision to stick with Kirk was the least worst option.