Points couldn't be distributed between teammates midway in the game. If it could, that would be the first thing the K♣ team do when they regroup at the base after losing consecutive battles in the early game.

Any change of point from either team would be broadcasted by the PA. Kyuma knew he would win because he remembered Arisu's points when they battled previously. Arisu had about 5K points, and he had 14K points at that moment. After that, the only battle that happened was Kuina vs Maki which happened right in front of Kyuma's eyes. Thus, he knew that Arisu hadn't done any battle and his points remain unchanged.

The player team did get a 2,500 item after that, and Kyuma couldn't possibly know who the individual who obtained that, but even if it was Arisu, his points would just be around 7K, not even close to his 14K points.