If he is, it's in the guise of a Trumpster.
That would be the conclusion the facts would support. Since the majority of the right's base do not want Trump, and have clearly stated for months now they/we will not vote for him, it would make sense for Sanders to promote him on right and moderate forums to create further division, prevent any alternative from arising ensure he wins the GOP nomination... but loses the election.
Many of us tried to tell people that Romney would not win without us. They "knew better." Turns out that we stayed with principle and Romney lost. We have told them the same thing again.
It seems they simply cannot be taught.