I don't think it's actually that weird. Perhaps "claim" rather than something a bit more neutral like "state" or "report" reflects a bit of conscious or unconscious bias. But otherwise it seems like responsible journalism to distinguish between facts you and your colleagues have been able to establish with reasonable certainty or confidence from things you've just been told by a single source who at least theoretically may have a reason to be less than completely truthful.
I generally agree with this. But what most likely happened, it seems to me, isn't the only consideration in how a careful, responsible journalist would present it.
Like how they kept reporting that police "claimed" Sandra Bland hanged herself, for weeks, when there was never even the slightest reason to suspect otherwise? Careful and responsible are not the words I'd use to describe the way the media reports on these cases.