Wait what?
Is the argument... "hey kowtow to people who are stomping their feet?" Because that seems like a pretty bizarre strategy.
I have seen multiple leftists attempt to deploy this argument on the board recently and they have mostly fallen over themselves due to not understanding the initial conditions necessary for it to work, so I'll spell it out correctly in the hopes that it will help them in the future.
IF you believe that there are a large contingent of voters who will only vote for a particular Democratic nominee (larger, specifically, than the equivalent contingent for any other nominee),
AND you believe that it is important to win as many voters as you can in order to win the general election,
THEN you should support that nominee in the primary in order to maximize your chances of winning the general.
One way to fill in the blanks here is:
IF there are a lot of moderate centrist Democrats who will only vote for Biden because the other candidates are too far to the left,
AND you want to win,
THEN you have to vote for Biden.
When you put it this way it's called "electability," and this is a very common use of the argument. Especially in 2016!
But you can also fill it in another way:
IF there are a whole lot of Bernie or Bust voters, way more than moderates or Tulsi or Toodlers or whatever,
AND beating Trump is a moral necessity,
THEN obviously you have to vote for Bernie in the primary.
You can call this "blackmail" or "entryism" or whatever you want but it's the same exact argument. So the question is whether you really believe that there are that many Bernie or Busters and whether we need them to win.
If you check the latest polls the only supporters who would abstain from boring are Yang's and Sanders'. That unbelievable to me.
Personally, I don't think those polls are reliable at all. People's self-reported willingness to vote for another candidate, in the middle of a contested primary, before the convention, campaigning, endorsements, and all that stuff, is in my view a basically valueless piece of data.
If people are still saying they won't vote after the convention, you should be worried. Of course, it will also be too late by then.