Maybe Pretty Boy did, indeed, take it from behind before he married a "beard". He sure seems preoccupied with looks and fashion.
I suspect that Sen. Rubio is doing this because he indeed has nothing to lose. He more than likely knows that he, much like Sen. Cruz is ineligible for the Presidency. He is a natural citizen, not a natural born citizen, thus is exempt for the office of President. So, the GOPe can get him to do any zany thing that which he is indeed qualified to do.
And he is more than happy to do it.