Mike, I think Josh is saying that while Bill Clinton may have had good reasons for getting so involved--his bond with his wife, the effect of her campaign on his legacy, etc.--they're all his problem, not ours. As Josh says, that's what makes dynastic politics so fraught--your loyalty to your family member's ambitions conflict with your responsibilities to your party or your country. They both should have thought about that before she ran.
The bottom line is that these loyalties, understandable as they are, involve Bill doing a lot of things that are unbecoming for a former president, which is disheartening. Particularly if, like me and Josh, you were a pretty huge Bill Clinton fan going in. (And, for the record, I wrote an admittedly fawning piece about Bill back in December. It honestly reflected my feelings at the time, but has been largely been overtaken by events.)
Also, I'm not sure it's releveant whether Bill's efforts have ultimately helped or hurt the Clinton campaign. The problem (for me in any case) is the unseemliness of him exploiting his stature this way. Not whether he's successful or not. By analogy (and I admit it's a flawed one, though it gets at the logic of what I'm arguing): I don't think we'd want the husband of a plaintiff serving as the judge in her jury trial and advocating on her behalf from the bench. Those efforts may provoke a backlash from the jury and sink her case. But the spectacle wouldn't exactly increase confidence in the judicial system.
Update: I thought this was obvious, but, just in case: The headline for this item is intended to be slightly hyperbolic. I'm not saying Hillary shouldn't have run unless she and Bill agreed that he wouldn't campaign for her, which is a preposterous thing to expect. (For what it's worth, that fawning piece I linked to was based on one of Bill's appearances on her behalf!) I'm saying Hillary shouldn't have run if she and Bill didn't think he could resist these unseemly hardball tactics. He seemed to be pulling it off before Iowa. Not since.
So the "stay out" portion of the headline should read as "stay out of the muck," or whatever. Not stay out, period...