Not that I'm one to get bogged down in 'political correctness' but just so we're clear "Bernie Bro" is a politically-invented pejorative with sexist implications (In that it implies sexism on part of the bro), thus I would argue it's a little unfair to use it in regards to people who happen to like Mr. Sanders or agree with his political platform.
Well, yes, it wasn't meant for anyone who liked Sanders, but it was clear that there were some Sanders supporters on social media who put far more effort into raging at Clinton, and anyone who questioned Sanders, than they would into actually organizing, doing any sort of GOTV efforts, or anything else. Even other Sanders supporters were catching hell from these people when they said anything even slightly critical of their preferred candidate. "Bernie Bro" was the term for that particular subset of voters.
As for the nomination being rigged - no. What happened was that a lot of Sanders supporters had no clue how primaries worked, and they took ordinary things (eg. closed primaries, voters being removed if they didn't participate in several elections, registration deadlines) as a personal attack and a conspiracy - even when the DNC had little or no control over the rules being objected to. Granted, the DNC definitely grew hostile to Sanders when he refused to cool it even long after it became clear that Clinton had won decisively. But that's pretty normal for party politics.
