There's generally a tacit agreement among Republicans not to do this sort of thing to each other (often relevant when you need to meet signature requirements in deeply Democratic districts, for example). The Rubio camp is either getting really, really desperate, or will lean on this guy to stop it.
You really have to wonder about the description of any election method which begins with the words "There's generally a tacit agreement...". This process ultimately determines who will sit as President of the United States; tacit agreements should have nothing to do with it. I really have no idea why our election process is so wonky. I mean, really, can't we just get our act together and decide on a reasonable process?