Yeah i'm sure this has a lot of impact seriously. Also some of Isiah's crazy moves are to blamed on Dolan who gave him full power to do whatever he wanted.
If Lebron goes to NY, the quicker people start to forget about Isiah and his mistakes. If Lebron wins a championship that is what people will be talking about, not how Isiah helped to ruin the team. If Lebron goes and doesn't win, then the fingers start getting pointed at Lebron. It's win-win for Isiah.