I wonder if other JFK airlines (DL and AA) are being so callous.

The whole avoid JFK thing is a little overblown as it takes a very specific wind to force them to use only one runway. At other times the construction is no big deal - remember JFK has 4 runways and only 1 is being renovated. Usually they use 2 simultaneously and sometimes 3, so most of the time construction on one isn't a big deal. People on twitter need to calm down!

That said, B6 should not behave that way. JFK is their hub and they ought to be a little more prepared during this period to accommodate pax on the few days when the wind acts up and takes JFK down to 1 runway. They went through this is 2010 after-all, when another of JFK's runways was closed for a similar period of time.