I doubt it. The media was just starting to vett Santorum.
Eh, the media had already labelled Santorum an extremist at that point (which they aren't completely wrong about, by the way), so I doubt that much more vetting would have rolled him over.
The thing was I knew a lot of high-end Romney supporters (and even many of those in the campaign) who were in near panic mode before Michigan. If Santorum won that and actually won Super Tuesday much of Romney's 'elite' support would have fled simply because if Romney couldn't beat Santorum in critical states (one being Romney's 'home state') he couldn't win in the General even if he pulled it off against Santorum. Romney's win in Michigan really calmed down his people.