As to the larger question, I believe that journalists should not give to campaigns. There is too much potential for conflict of interest. I suggested to a fellow journalist today that perhaps the case could be made that a food critic, perhaps, might be able to make such a contribution, to which the journalist pointed out that in today's changing journalism world, who's to say that food critic wouldn't be pulled into political coverage at some later date?
While the story points out giving to both Republicans and Democrats, and points to an egregious Missouri example, it's clear that more journalists give to the left than the right. That's not surprising, as various studies have indicated that more journalists are left-leaning. While that's not proof of bias, it's an example of why it's so easy for the right to play the bias card.
Is it the constitutional right of journalists to contribute to political candidates. Absolutely. But each time journalists do so decreases their credibility with their readers and viewers.