Unfortunately, you are right.

What space nuclear advocates sometimes miss is that the opposition is NOT only due to perceived safety/health risks. Even if you could honestly convince all the anti-nuclear types, so that they too agreed the risk was zero, you would not win them all over.

Inevitably, space nuclear systems get caught up in the politics of military applications of nuclear power, and militarization of space. There are conspiracists who think things like JIMO are just fronts for developing technology for son-of-SDI laser battle stations. And even those who don't, still see big political points in attacking civilian space nuclear systems. You generally can't touch whatever the military is doing, since any such programs are likely to be "black", or at least to have much stronger political support. So by hitting the Administration (whether that be Bush, Clinton, or whomever) over it's use of nukes for space science, you take out some of your frustrations that you can't hit the military nuclear applications that you really care about.

Stupid yes, but such symbolic politics are by no means limited to the anti-nuclear left; it's pretty standard rules of the game in our democracy and you can find just as many examples on the right.

Nuclear is a giant "Kick Me!" sign politically.

That's what worries me about NASA's newfound willingness to go nuclear. I think it is absolutely the right call on the merits, but worry it will leave us with nothing when Prometheus gets killed eventually.

Since the reasons are only slightly due to the (irrational) fears about safety, you can't quiet the opposition through any technical fixes and technical rhetoric. There really isn't anything you can do, since a lot opposition doens't really relate to NASA and it's systems.