If the protagonist wins, will the blue lock project end? beyond that, I know it may seem strange, but I can imagine that Sae's relationship with Kira could be one of mutual friendship/respect.
Ego said Win or Lose as long as the match gets greenlit he already won.
His purpose is to let Blue Lock Shine to Foreign Investors for the next Tests.
And See if more players make a breakthrough by battling Kira.