If some day someone can actually demonstrate that misogyny actually WAS a big part of why Hillary was disliked (as if the life long corruption, war mongering, dishonesty, scandals, job failures and flip-flops and tarnished Clinton brand were barely noticeable) then it still wouldn’t be incumbent on Bernie to apologize for any of that. If anything, he was far too easy on her and nothing he did or said suggested the slightest he was misogynistic or that many of his followers were either.
You might as well ask him to apologize for starting WWII since that was also not within his power — or his responsibility.
As for the mythic Russia being responsible for her loss, even the McCarthyite Dems who’ve pushed the Clinton-originated BS Russian narrative have woken up to the fact that it’s a losing strategy. Even Chuck “the establishment” Schumer just clearly said it’s time to stop blaming the Russkies and own up to why she really failed in 2016 — a poor campaign that didn’t resonate. I’d take that further — more Clinton ineptitude, the true hallmark of her career as FLOTUS, Senator and SOS.
Likewise, whatever the Russians actually did do — it is still not Bernie’s responsibility nor is it his responsibility to monitor the entire Internet and track down bad things people say about the Clintons and be the ultimate authority which are true and which are not and then render is public judgment.
For every dweeb that cited the Clinton Body Count there were 10 Berners who cited HRC’s pointless destruction of Libya and that is just a sad fact of her record, even if you first heard about it from Putin himself.