He thinks the way for democrats to advance their agenda is, somehow, to run as center-right politicians, and then suddenly do a bunch of liberal stuff when they're elected, without building any popular support for it, much less defending it against right-wing attacks.
As the GOP has ascended by relentlessly pushing its message and building a base on that, he tells Democrats the last thing they should do is take a principled stand and advocating for it. I'm sorry, but he's been of far more use to the GOP than the beliefs he claims to hold.