Don't see the argument that Sanders isn't a stronger general election candidate. All it comes down to is he won't survive the Republican attack machine. If he's so fragile, why has he survived Hillary's attack machine? She has made the case he's unelectable and aggressively gone after him yet he still boasts higher favorables and better general election numbers.
What Clinton attack machine? Sanders have gone through this primary unscathed. You think Clinton pointing out Sanders voted for bill A over bill B is an attack? If Sanders is the nominee just wait when the GOP SuperPACs stop airing ads in support of Sanders and start airing ads that say "Bernie Sanders, a self described socialist and supporter of communist dictators, wants to take away your private health insurance and raise taxes on the middle class and poor." Incidentally, about 75% of this statement is true!