The Trump campaign desperately wants New York to be the end of the line for its enemi--er, opponents. Of course, the campaign has tried to make it the end of the line a few other times. Remember the South Carolina aftermath? It was supposed to be smooth sailing for Trump, and it turned out not to be so.
As I've said before, the only way they can win is if they can discourage the NeverTrump movement into thinking their voice doesn't matter anymore so that they stay home, or that the delegates see the inevitable and support Trump because that's their only realistic option. They're slowly running out of time.
This is psychological manipulation. Trump's campaign folk are not fools. They did not get this far with a toxic candidate by being incompetent fools.