Rabbits don't always avoid plants that aren't good for them. My guys finish every bit of their salads, even though there may have been a missed 'rotten bit' and they end up with gas. Pipp will know to be cautious next time (she won't eat the offending veggie again for days or weeks), the others just continue gobbling them up.
If rabbits are used to be fed food and treats and they taste good, don't count on them knowing its not good for them.
Right now we don't need examples of rabbits eating the stuff, we need to research the effects and toxic properties.
PS: The fact that rats didn't 'drop dead' after ingesting a bunch is a poor indication of its safety. Rabbits have totally different systems and reactions, and those rats may have had other effects than death. And as stated, it may have made them darn uncomfortable. Photos of irresponsible people just testing the stuff out on their rabbits is near-criminal in behavior alone.