Fear of conflict, absurd belief in the importance of maintaining respect in rotten institutions, unwillingness to critique elites of any kind... I'm not sure precisely what the reason is.
When these types of things happen, a lot of people say, "imagine if this was a Dem," as a criticism against journalists. This is not a meritless complaint, as the press and their favorite sources tend to kneecap vocal Dems and obscure the wrongdoings of Republicans. But the other part of this is "imagine what Lindsey Graham would be saying" and asking why Dick Durbin [or whoever] isn't doing similar.
The political press is generally bad, but it isn't actually their job to fight your battles for you.