The only reason the Knicks are in contention to land Bosh is because the rookie head coach David Fizdale was an assistant coach when Bosh was a member of the Miami Heat. They have a history but I don't think that will be enough for teams to risk signing Bosh.
Bosh had to retire due to multiple blood clots. NBA doctors haven't cleared him to play in the NBA and teams are worried about the worst-case scenario happening. Besides the health risks, Bosh is much older now and hasn't played in the NBA since the 2015-2016 NBA season.
The question that is begged to be asked is why would the Knicks sign him? Right now, the Knicks are trying to rebuild and develop their young players. Signing Bosh would take away minutes from the younger players.
There is no win now mentality in New York. Most of the fans expect this season to be a waste. Without their best player, the Knicks won't be able to compete with the rest of the NBA teams. And Bosh won't be able to replicate Porzingis's production.
As of right now, Bosh is giving himself until the All Star break to decide whether he wants to come back or not. Surely, there will be one team that will give Bosh a chance.