Is this what happened in SC?
I voted on the site for Biden and then looked at the results. Sanders got 71%, followed by Yang at 16% (he dropped out before SC) and then Warren at 13%. Everyone else, including Biden, was sub-1%.
It appears the rank and file think Bernie is the candidate they'd rather run against.
I suspect the GOP party leadership has a more nuanced view. But who knows. Their ideological bias and penchant for cheap shots might cloud their judgment, too.
If the objective was to push Sanders to victory it certainly failed.
Who knows? In states with open primaries, you wouldn't even need to change your party registration beforehand.
But aren't the strategic republican voters voting for Bernie?
Opinions vary, but I think they understand that Biden would be easier to beat.