O'Reilly has always been for gun control. I don't listen to him anymore but I can't recall him ever speaking up for any gun rights except the proverbial duck hunter.
Fox is hosted in NYC so I would not be surprised if many on their staff are brainwashed and ignorant about guns and gun owners.
Fox seems to have taken a left turn of sorts a few years ago. More and more liberal opinions to "balance" rather than just seeking the truth and facts.
Events and issues such as these reveal who the friends of liberty and truth are, and are not. Short list of public friends but a mile long line of gun owners voting with their wallets.