I'd answer by referencing the Vinaya.
Not because journalists are bound by the Vinaya;
nor because the Vinaya is intended to regulate the behaviour of lay society;
but because I find it instructive ("if the rule is good enough for monks, or necessary for monks, then...");
and because if the question is asking for an answer based on a reference, perhaps there is no specific doctrine in the suttas, so the vinaya maybe the nearest thing you'll find.
If you read a copy of the Vinaya e.g. here you'll see it's not necessarily "wrong speech" to bring an accusation.
There are rules about it -- doing it at the proper time, for example, and with permission to speak (and I suppose that anyone who reads an article is thereby implicitly giving the author permission to "speak").
Making unfounded accusations is wrong, but,
As under Sg 8, there is no offense if one makes the accusation—or
gets someone else to make it—when one thinks it to be true, even if the
other bhikkhu is actually not guilty of the offense.
Summary: Making an unfounded charge to another bhikkhu—or getting
someone else to make the charge to him—that he is guilty of a saṅghādisesa
offense is a pācittiya offense.
I'm not sure what "divisive" means, I suppose the canonical example would be Devadatta's splitting the sangha by arguing against the Buddha's vinaya.
Perhaps this sort of thing is what politicians (rather than journalists) do, if ever they try to create factions in the population.
I suspect that the intention in reporting wrong-doing isn't necessarily divisive -- in a community that's united by an ethical code of conduct, perhaps it's any misconduct (i.e. not the accusation) that's divisive. The accusation and so on may be part of the corrective or unifying mechanism.
I suppose it depends. Just as there's both Right and Wrong speech, Right and Wrong livelihood, there are probably right and wrong ways to report on the conduct of public affairs, and criminal activity, and other matters of "public interest".
I don't think you can say, "Oh it's wrong to ever accuse anyone of anything, that's divisive!"
Of course a monk maybe shouldn't be embroiled in political topics: but the question is about journalists.