The situation in Libya was mishandled by the incumbent administration and Mitt Romney is running against that administration, so of course he'd take full political advantage of the situation. Republicans jump on the mistakes of Democrats, and Democrats jump on the mistakes of Republicans; every tragedy becomes simply the way for someone to get a political advantage.
Yes, I believe that Mitt Romney politicized the tragedy in Libya during the second Presidential Debate. During the debate, Mitt Romney specifically criticized Obama in not acting fast enough on intelligence and he indicated that either Obama purposely didn't send aid in time and lied about it, or that he wasn't competent enough send aid quick enough.
Mitt Romney tried to get President Obama to say something awkward about the Libyan consulate attack. The only thing Romney got was a mudslinging. Romney's way of politicizing the deaths of four people would be like John Kerry saying George W. Bush mishandled 9/11. It was tacky, tasteless and ill-timed. In terms of a foreign policy debate, Romney utterly failed to keep up with the president.
Romney made a mockery of himself and his goals by turning an unexpected tragedy into President Obama's folly. The misfortune in Libya was turned into a simple chess piece by Romney when he politicized the event in the presidential debate, attempting to convince Americans that Obama should have had the unprecedented foresight to acknowledge a terrorist plot against the US on foreign soil.
There is no doubt there is a massive cover up here. The movie about Muhammad was designed to take the rap for it all but things got badly out of hand. Notice the press and white house on Day 1 were comfortable with the insulting movie story. Obama even apologized to Muslims, which to be honest shouldn't have happened.
Mitt Romney was a man who was in the world spotlight as candidate for president of the United States of America. The tragedy in Libya was big news, it would be odd if he didn't put out his opinion on such a hot issue at the time. There is no reason that we should attack the man for that.