We can dismiss them and laugh them off as just "crazies" or zealots but we do so at the risk of burying our heads in the sand and underestimating an enemy which not only wields political and economic power but is totally committed towards closing zoos and doesn't give a damn about the implications of this to conservation.
I counted people on the photo. There were about 30 protesters - less that 1/100 of visitors to Jardin des Plantes every day.
Knowing the subculture of animal rights activists, they easily switch to different targets and often try to randomly throw sh*t here and there and see if it sticks. Zoos which are too timid and self-excusing easily encourage more unjustified attacks. I think zoos do best by unapologetically explaining their role, not only as captive breeding but education, support of in situ conservation and general raising interest in wildlife. And loudly calling out a lie or distorting the truth whenever activists do so. It wouldn't harm also to ask anti-zoo organizations to prove their contribution to conservation and science credit themselves. Anti-zoo organizations are very vulnerable to their own poison - being shown as unethical and losing face.
And yes, zoos downplay their real role by presenting themselves only as breeding centers of endangered animals - which is actually not the biggest contribution to conservation of modern zoos.