The left railed against O'Reilly, for months, and the Murdochs did nothing.
It wasn't until the sponsors left the show that they did something.
O'Reilly is a lecher. But he was the Mudoch's lecher and he brought in hundreds of million $$$ to the coffer. And as long as he did so, they didn't care how he treated women in general and FOX employees in particular.
Once the sponsors abandoned him, there was nothing left for the Murdochs to do but cast him aside.