At the risk of belaboring the obvious,
Ellery Queen is a TV show, even if it doesn't always look like one. And yet TV hasn't been much of a factor in the context of the stories. Characters listen to the radio, go out to the movies, go out in general. They don't sit on the sofa and stare at the tube. There's a certain amount of realism to this, as the stories take place mostly in 1947, several years before the Lucy-driven explosion in TV set ownership.
Once previously television played a major part in the story. That was in the pilot movie, where what was broadcasting at a particular time turned out to be the key to a dying clue. In the pilot TV was treated as a gimmick, a fad that would pass in a few months without leaving a mark. There are words to that effect in this episode as well, notably from the victim. But by this time the dismissal has lost any force it may have had. TV may not have hit its stride yet in terms of viewership, and there are clearly some technical refinements that will have to be made. Yet the infrastructure is unmistakably there. It's not going away.