Although I wouldn't "call anyone out", I do think it's ok to say that calling in sick on Christmas if you don't need to is not ok.

I worked almost every Christmas from about '90 to 2009. I remember one year at CommutAir being holed up in Utica NY in a room where the heat wasn't working and the front desk said they had no other rooms so I spent 10 hours in the lobby and skipped a shower in the morning.

Point is, one doesn't need to "call people out" to simply make the point that calling in sick on Christmas if you don't need too should not be considered an ok thing to do. Now having said that I will admit that I had to call in sick on Thanksgiving this year so I know things aren't always what they appear and one can not assume anything until you "walk in the other's shoes".