So many little gripes
* They would not be pulling in low-level random people for a last-minute evacuation to Greenland. Unless Gerard Butler's character is some world-renowned expert in structural engineering, they would not have space for some ordinary engineer and his family or bother flying them to Greenland. Maybe top-of-their field experts, but a lot of this expertise existed in the military already and would be better suited to what would be a military-led recovery effort.
* Why Greenland? Is this just some dumb nod to "hurr, durr fire won't work in icy Greenland"? Thule airbase is also on the coast and probably vulnerable to the "1000 foot tsunamis".
* I would actually expect a lot more effort to at least try other potential deep underground survival locations in the continental US. Mines, caves, mountain tunnels, Cheyanne mountain complex. Even if deeply improvised, they might provide sufficient protection from the heat/blast waves. Lots of other countries apparently (Beirut, even) appeared to have survivors with radios that worked. Plus it greatly simplifies the logistics of moving people and material if they only have to go local, vs. some crazy airlift.