I think this is a good idea.
Grand Slam regulations state that if a player pulls out late due to an injury, they are allowed to keep 50% of the first-round prize money (which is £80,000 this year, meaning they get £40,000).
The other 50% of the win (£40,000) goes to the lower ranking player from that qualifying round who takes their spot in the main draw.
Before this rule came in, injured players would frequently walk onto the court irrespective of injury just to collect their guaranteed first-round pay check.
Then they would retire from the match after just (say) two games.
This frustrated fans, broadcast networks, tournament organisers and the other player.
The 50/50 split gives players an incentive to be honest about their injuries early enough for a healthy player to take their place who otherwise wouldn't have had the opportunity to play.
I have no idea why anyone might be against this.