Rubio would side with Brownback not Huntsman. He opposes gay marriage and supports an amendment banning gay marriage.
Huntsman still thinks its a state's issue. Rubio isn't going to ruin his credibility in the Republican party, especially if Huntsman loses. He does not want to be seen as someone who cost the GOP yet another chance at the White House. Huntsman is still very conservative on fiscal issues. Rubio knows better than to sink the election over one issue. The GOP is still licking its wounds from 2012
If I've read correctly it sounds like Romney lost to Obama by a comfortable margin and couldn't win Indiana?