If you are clueless why he did that, the time was about to run out, so the disadvantage is on the T Side. He was able to kill the bomb planter and it takes four seconds to plant the bomb in CS2 so with only less than four seconds remaining, the remaining T Side player's objective now is to just kill the CT player before the round ends so they will win the round. Too bad for the T Player, the CT Player jumped off the map and killed himself instead so he can avoid getting killed by the T player before the timer runs out, haha.