That was a different time. Many didn’t realize until well after the election what had happened. And, Bern meekly accepting the rigged outcome was also a factor.
The Bern bots are now well aware of what the dnc did to them last time. They have once again rallied to him. Many will not accept being screwed over again.
Of course, not all will react that way. For many their TDS is all-consuming but, enough will be angry enough if they are screwed again to be a problem for the dnc.
The dnc knows this and they are concerned about this.
I agree that the Berniebots will not just vote Democrat if they believe he is cheated again; probably vote Green Party...