If Rubio wants to run for re-election to his own Senate seat, he still has time before the filing deadline.
But he knows Florida is done with him, so he has nothing to offer Trump.
Before Cruz dropped out Trump could have possibly made the Rube VP to obtain his delegates, now he doesn’t need them. If Trump thinks he needs to secure his right flank Cruz, Walker or Scott are good choices. The Rube is only an option to throw a bone to the scum that worships at the alter of the Republican Party.