The essential cause of Obama not likely to be a lame-duck anything would be if many of us sat out the election rather than actively vote ABOOR with the goal of making the winner have the smallest plurality possible. Maybe we couldn't survive, as the Chicken Littles claim, another four years of Obama, but maybe we could, especially if the conservative side of the Republican party grows stronger.
One thing for sure: the Republican party would die if its most powerful representative advanced and defended nationalized health care, on-demand tax-funded abortion, forced acceptance of open homosexuality throughout society, and cap-and-trade "save the planet" environmental regulation. Regardless of wishful thinking that Romney might come around (liberals are so good at that! NOT!) it's what anyone who votes FOR Romney, would be authorizing the Republican party TO DO.
That is a losing proposition, period. Guaranteed.
Regardless of what picture the MSM presents, at least half, likely much more, of productive Americans think Obama's a crappy president and think statist liberalism stinks. If enough people vote ABOOR (anbody but Obama or Romney), whichever socialist who won would have a plurality; assessing Romney, I'd prefer Obama won with, say, 40 percent of the vote (unless a really good 3rd party candidate, like Palin or Newt, jumped in -- there'd be zero to lose and everything to gain -- no guts, no glory). A president opposed by the majority of actual voters would be weakened politically.
As for the SC, look at Romney's record. Thinking he'd appoint anything other than an activist liberal mindset is wishful thinking.
While I agree with your thinking mostly, and agree that Romney would appoint more Souters to the Supreme Court (rather than Obama's Kagans -- so what?), I feel obliged to point out that being a minoritarian president didn't stop Slick Willie from pushing Hillarycare and midnight basketball (gun-ban list, which btw is still operative in part, the Dems spread the pieces around to avoid the sunsetting clause for some of their goodies).
Still, the Justices Romney would appoint would be, if less toxic, less likely nevertheless to be opposed by conservatives and other Republicans in the Senate, as Kagan should have been opposed.