Palin is anti-gay marriage, nobody is arguing that. But she NEVER talks about it unless forced to answer a direct question, she wastes no political capital on the issue. You look at 100 random Google stories on Palin, not one of them will be about protecting marriage. Again, she is no Obama or Romney, but she is not a Santorum or Bachmann either.
Ever since the 2008 election she has been ignoring the issue as the gay lobby made giant strides in politics and culture.
You may want her to talk about it more, but she does it when the subject is in the news, for instance for the 2012 election.