He's tolerated by the MSM. They'll defend him against attacks from the right but they don't want him to be president, so in that sense, they don't support him.
Only after Trump became popular did the MSM dishonestly portray Senator Sanders as an outsider.
It's basically true that Sanders is part of the Washington Establishment, but at the same time, it's a little embarrassing to keep saying that Trump or Cruz is so massively anti-Establishment and the guy who had a Soviet flag on his wall when he was mayor is a pillar of the American Establishment. It looks like special pleading: my guy threatens the powers that be and nobody else can.
There are different kinds of Establishment or branches of the Establishment. Somebody who's found a cozy home in Congress can still rattle Wall Street. Somebody who frightens Washington DC can be quite acceptable to corporate elites.
The Washington establishment threatens businesses. They extort billions of dollars from businesses by threatening business. Sanders is a communist but so are many members of the Washington establishment. Communists paid for Bill Clinton's trip to Moscow in 1970 to meet with Soviet Party officials. The Clintons received billions from Communist China and gave China U.S. military technology. John Kerry worked with the Communists throughout his career. Democrats sabotaged Reagan's cold war efforts and helped the Communists. Most Democrat establishment types are Communist sympathizers.
Senator Sanders is the ranking Democrat on the Veterans Affairs subcommittee. He has used his position to defend corruption by insiders in the V.A. and prevent veterans from getting medical care.
Senator Sanders is a corrupt Washington insider. He is a member of the Washington establishment. He is for the status quo and Obama administration programs.
The MSM do support him and his position as Senator. The MSM dishonestly portrays him as an outsider. It is a lie.