From the article linked at that Deadline website ...
In January MSNBC president Phil Griffin said the ideas expressed in Buchanan’s book put forth “aren’t really appropriate for national dialogue, much less the dialogue on MSNBC.” Buchanan wrote today in an essay on the website for The American Conservative magazine, which he co-founded: “In the 10 years I have been at MSNBC, the network has taken heat for what I have written, and faithfully honored our contract. Yet my four months’ absence from MSNBC and now my departure represent an undeniable victory for the blacklisters.”
"Aren't really appropriate for national dialogue"? An author questions the future of his country and his ideas "aren't really appropriate for national dialogue"? That's pretty gutsy for MSNBC's head honcho.
Then again, for a network that preaches progressivism, perhaps that's not a surprise.
I suspect Buchanan still will be seen and heard in all sorts of venues, including his syndicated column and his appearances on such programs as "The McLaughlin Group." It will be more of a loss to MSNBC than to Buchanan.