I think that if a journalist or columnist acts like the opposition, then the politician in question and his supporters will treat that columnist _like_ the opposition.

Certainly the author has a point.  A very good point, to be honest.  However, tone and the manner in which she makes it is important.  By the manner in which she makes her point, she sets herself up to have anything she says simply dismissed by anyone who doesn't share her bias.

Of course, making this point _without_ appearing to be part of Mr. Trump's political opponents would be challenging to say the least, but I think that her commentary would be far more effective if she appeared be at least making the effort to be unbiased.