Marco has 167 delegates so far. And he is not releasing them today to any one. If Trump is at 1100, those 167 delegates pushes him over the line.
He helps Trump with hispanics (maybe) but the big thing for Trump would be getting his delegates. And since he's all but done for politically in Florida he's probably more then willing to make a deal with Trump.
It was posted early on that Rubio’s delegates become free agents. It’s up to each of them who they want to switch to, not Rubio.