Why bother, they'd probably tell you that it was some legal battle and moral superiority that allows them to Protest. Look at the comments Zell Miller made at the RNC. Look at how well they embraced those. Logic and reason and absent of the left, that's why they aren't right :)
I agree the effect would likely be minimal, but who knows, maybe there are a few who got caught up in the propaganda and might be open to taking an honest look if confronted with the sorry truth of the "protestors". If good men do nothing, the trash has an unimpeded path.