The vast, vast majority of Bernie supporters are cool-headed folks who will do the logical thing come November. They realise that Hillary and Bernie agree far more than disagree, and they don't buy into the asinine, reality-challenged rhetoric suggesting that she's a "secret Republican" or "Republican-lite." When the nomination is settled, Bernie is going to acknowledge this for all to see. He'll reason that a Republican winning the White House would be disasterous for the long-term prospects of his vision being fulfilled, and most of his supporters - while not necessarily being enthused - are going to agree with his assessment.
I don't think folks are attacking all Bernie supporters. I see that some language is loose and non-exact, lacking an explicit "NotAllBerniefolk" qualifier, but my suspicion is that these attacks are against the kookier segments of his base. The math-challenged, the ones who refuse to acknowledge hard realities of our political system's structure, the ones who seem a bit too eager to cling-onto old Republican attacks.. those folks are going to draw mockery. This shouldn't exactly be a shocking thing.