That's an awful argument because there ain't a single Republican alive who had shyt to do with the end of slavery.Not the best argument I have ever heard you make tbh. Using that argument one could say trust the GOP because they abolished slavery. Bernie has often had a one size fits all approach to politics that isn't translated in the real world. Liz Warren adjusted and took up well thought out, explained nuanced positions. Bernie feels like he just keeps giving more of the same. I may be wrong, but that's how I see it based on what I read and see.
And why make this a Bernie vs. Warren issue? I'm pro-Warren and pro-Bernie both. It would be shooting ourselves in the foot to attack some good thing a candidate did just because we like some other candidate better.
Like I already said, saying that Bernie fought for civil rights for Black people doesn't define the argument. It's only the start. But it's a good start. Whenever you're trying to answer the question, "is that person genuine about what they are saying or are they just being politically convenient?", one of the first things you look at is, "Okay, well, what were they doing before it was politically convenient?" And the answer is that Bernie was fighting on the side of Black people back when it was extremely non-convenient to do so. That doesn't tell you that Bernie will make the best president, but it does give you the impression that Bernie's stated concern for the welfare of the Black community ain't just a show for votes.
Similarly, Clinton campaigning for Goldwater doesn't prove that she won't stand up for Black people. Of course people can change, and I honestly believe that Clinton changed. But did she change when it was hard, or when it was easy? And when you look through the rest of her career, did she stand up for Black people when it would have been hard (like 1990s fights regarding black criminality and welfare reform, or in 2008 when Obama was under attack from racists during the primaries?) or just when it was easy (making promises while campaigning)? Clinton appears to me to take the politically expeditious route far too often.
Again, nothing Sanders did in the 1960s proves his case. It just sets the bedrock for what we can trust regarding his case. Does that make him a better candidate than Warren? Of course not. I would probably prefer Warren to win the presidency at this point. But I would be perfectly fine with Bernie too. We should only shyt on candidates when they're doing the wrong thing - shytting on candidates who are doing all the right things just because we prefer someone else is misguided energy, yet all the way since 2015 it seems to be where a lot of the anti-Bernie hate has developed from.
If Bernie hadn't dared to stand up to someone else's favorite candidate, then his fight in the civil rights era would be seen as nothing but positive. People talk about plenty of old things in campaigns - McCain, Kerry, and Gore all had their Vietnam service come up as a campaign issue, while Trump, Bush, and Clinton had their draft dodging come up, and Vietnam happened just as long ago as the CRM did.