It does bring up a question, though... why would Romney even bother voting to Impeach to impeach the president, knowing that the effort was doomed to failure even before it got to the Senate?
Sure, he just gained some temporary respect from Democrats and moderates, but those Democrats still aren't going to vote for him come reelection time because they likely still disagree with everything else he stands for. He's really just alienating himself from his supporters, which might come back to haunt him someday.