It’s a setup by the GOP-E to pave the way for Jeb 2016.
Not really. Perhaps the real answer is that the GOP-E works for a bunch of low-wage, wage-busting large employers to whom open borders is the Holy Grail.
If open borders is in fact a meta-policy (meaning, "this is our policy come hell or high water or hordes of invading Chinese, because this is our honeypot of prosperity and we will never give it up -- we will have cheap labor!!"), then it wouldn't matter if bending someone like Rubio to that yoke and breaking the GOP and the Tea Party on a wheel of massive new-voter registration handed the White House to the Communist Party of the Soviet Union for the next 200 years. Because a meta-policy means that the country can go to hell, but WE will have THIS no matter what!