Good lord people. SPLC has a cache of emails from Stephen Miller written to various people at Breitbart about reporting their stories with explicit white nationalist ideology. You don't have to like SPLC to believe the leaked emails any more than you had to like Wikileaks to believe the leaked DNC emails.
I'd encourage you to read the link instead of whatever kind of dismissal this is. They have leaked correspondence between Stephen Miller and Breitbart coordinating the latter's coverage with an explicit nationalist bent. Breitbart relies on Camp of Saints and VDare for their sourcing on policy stories. Have we already forgotten their "Black Crime" news tag?
They literally had a section on their 'news' website called "Black Crime" - the terms are synonymous. It's astonishing to me that the crowd would rather parse SPLC's phrasing or history rather than the documentary evidence that there are white nationalists making policy at the highest levels of our government and coordinating with one of Facebook's 'approved news sources'.
Not familiar with HuffPo but based on your examples of either middle of the road to corporate Democratic supporters I think the whole narrative of there being a bias against conservative news is a false victimization claim. There should be a bias against untruths, even wikipedia banned Breitbart and the Daily Mail as references.