He says he is serious. If he IS serious, then he has to differentiate himself from Hillary, which is simple because there are miles of daylight between them on virtually every aspect of the economy, on defense, national security, even the environment to the extent that he recognizes the need for a much more immediate, more aggressive program to mitigate Climate Change. And more.
For him to define what he is for and what he is against without identifying HRC's positions, based on a vast historical record, is pointless. For him not to question whatever position de rigeur she adopts for the purpose of the primary is not only foolish but would do a disservice to those who are campaigning with and for him.
For that ONLY serves the establishment, by allowing them to define the frame. It's like allowing BBB to declare that the ONLY difference between candidates Obama and Clinton was in their attitudes on defense. As if the entire PE came down to whether or not people felt 18 or 24 months was a better goal for getting out of Iraq... It ONLY serves Clinton to say such things. It ONLY serves Clinton for Bernie to put forward his Agenda and the many well-established attitudes and views he has while idly allowing Clinton to pretend she's just a smidgen to his right, which is the ENTIRE dishonest D establishment game plan in every election. Which is why they must be defeated.
In addition, if Bernie does define his positions in relation to HRC's, and he is completely honest, it WILL paint HRC in a bad light. It can't not. And there's no other way to go and still be serious about winning.
And let's not forget Jeremiah Wright, HRC will ONLY play politely so long as she maintains a comfortable lead. The moment any contention gets real, she AND her supporters, including those promoting a polite Sanders campaign now, will go after him with fangs, claws and garrots if they have to.
Please let's not kid ourselves.
Let's not pretend that this effort to force Bernie into a box where he can't expose the real differences, the critical differences, between he and HRC, between democracy and plutocracy, is anything but a thinly veiled attempt to secure her coronation without ANY contest at all.
It may not be pleasant to have them fight, but endless economic rape; increasing concentration of income, wealth and power; criminal warfare; and national security fascism is far from pleasant, too. And those are things this election is really about. He can't let the establishment pretend it's not, that one candidate will fight to put an end to these things, while the other will fight to put a kinder, gentler face on them.
I'm not saying he has to come out guns blazing tomorrow, but before too many months pass shit will have to get real or there will be no contest.