That’s not really how it works.
First, ABC doesn’t program sports just to “avoid having to get people to work on the holiday”. I’m hoping that was meant to be funny, but it comes off as naive.
Second, the newsroom does not get the day off. It still has weekend staffing. That includes assignment editors, reporters and photographers working on stories for the late news. A skeleton staff of producers, editors, writers, directors, on-air talent and technical people will still be scheduled during the day, in case of an emergency or breaking news. They won’t have a lot to do, but they’ll still be there, just in case. Small market stations might not do that, but at WABC, and I’m sure most other major market stations, that’s the way it works.
Newsrooms everywhere get a staffing break when Christmas falls on a weekend, because weekends always have skeleton staffs, compared to weekdays. So, Christmas scheduling on a Sunday is easier, even without sports to fill the day.
By the way, the people who went to work at 11PM on Christmas Eve, in miserable weather, to put together the morning show on Christmas Day probably don’t feel like the newsroom got the day off. Neither will the people who have to go to bed at 3PM on Christmas Day, so they can do the Monday morning show.