Not true. They can, but the FL delegates can only vote for one of them, not both Trump and Rubio for VP. they would have to vote for someone else for VP which could deny rubio enough votes to become VP.
But if nobody gets a majority of the electoral votes, the Senate chooses the VP from among the top 3, and teh Senate map favors the Republicans. 24 Democrat seats up this year, only 10 Republican seats.
Unless the ticket have 300 votes. Prez 300, VP 270.