Journalism is a business. Selling their medium pays the bills. You only have a few options:
You either say they have no responsibility, which allows them to do whatever they want to sell their product.
You establish that they don't have opinions about anything, and can therefore report without personal bias.
You can assert that they are completely capable of plying their trade without influence of the personal opinions they have.
If you think of a fourth option, let me know.
If the first is true, your argument is moot. It doesn't matter.
If the second is true, your argument is moot, it doesn't matter.
If the third is true, you have to establish that she included her personal bias in her journalism. You have yet to do that.