With Cruz or Kasich with their names still on the board at the Convention, and IF Trump doesn't make the first ballot, they are providing those delegates (and voters) a choice of a candidate.
I imagine they aren't really thinking about those poor “disenfranchised” voters that voted for losers, but they probably are thinking they can get those delegates.
I could understand this for Cruz - maybe, and if Trump loses everything remaining. But it is mathematically impossible now for Kasich to get the 1237. It just cannot happen.