Hey, reposting my comment from above:
IMO it's more harmful to give attention to fake articles like this cause it gives them credibility. Same reason why Warren's camp didn't comment on it either, it's just bad news to try and drive a wedge between two good candidates. Here is an example of our

Actual Script - ask candidate about issues that are important to them, talk about why you support Bernie etc.

Bernie Volunteers Community Norms -
"Never speak negatively about other candidates. We only point out policy differences. Remember: Policies, not personalities! We will not let differences of opinion in policy and strategy descend into a personal attack."

and here's our Video Call Guide where it states explicitly NOT to say anything negative about other candidates and to be warm and positive

Hope this gives a clear understanding of our norms and rules over at Bernie's call team.