Shemya is known for its wicked cross winds. The landing (getting the plane on the ground) had to be urgent because flying to Anchorage could have been a better option. Shemya would be my last resort alternate. Anchorage or turning back and going to Sapporo, Japan although that would be flying into head winds and take longer, perhaps. They could be there for a while.
“They could be there for a while.”
Delta put one into Cold Bay last year, due to an engine failure, population 108, with 250 new guests. Delta rented an AN224 to fly in a new engine, a fuel truck with fuel, and two loaded deice trucks, as well as equipment and mechanics to do an engine change on the ground. $$$$.
Shemya is a little better equipped.