Citation needed.
Sorry, I’m a scientist. 
Is there any evidence of bamboo shortages during the last X years, where X is the number of years that pandas have been primarily bamboo-eaters? Bamboo is a grass. It grows very quickly and easily. Barring human interference, it seems to me that it would be a pretty darned reliable food source. I don’t think it’s reasonable to assume, without evidence, that there have been shortages of bamboo in the recent past.
S’ok, I’m a skeptic myself.
Before I do some research, I’ll throw in that there are cycles of bamboo growth among the species panda’s eat that, IIRC, periodically cause shortages. I would also assume that bamboo forests are susceptible to drought, fire, and unseasonable weather. So I find it likely that pandas have managed to survive food shortages. Of course, there could have been many food shortages, and a lot of pandas just died each time.
Also, I don’t know if X years of pandas as primarily bamboo eaters matters here, since my argument is that pandas aren’t so entirely dependent on bamboo as they would appear in modern circumstances. The converse argument would have to show that pandas were primarily bamboo eaters for X years encountering no food shortages or other shortcomings from the diet such that they would have lost the ability to eat a more expanded diet.
Bamboos have an unusual reproductive system. Most species flower once in their lifetime and then die. All the individuals of a given species will flower synchronously at intervals of several decades (sometimes more than a century), and then all the bamboo plants die. The species then regenerates from seed. So by the nature of its food resource, pandas will virtually inevitably undergo significant food shortages every few decades. They are pretty much restricted to regions where there are at least two species of bamboo that do not flower synchronously.
Anyone, creationist or otherwise, who thinks pandas are peaceful vegetarians who shuffle around eating only bamboo has never seen the myriad YouTube videosof pandas attackingzoo visitors who got too close to the bars.
(Apologies if those are links to videos of the same event - our YouTube usage is limited here at work.)
Stop, you’re both right! Er, all right. But I admit I’d take a certain perverse pleasure in watching him stumble around in his mind first for an answer. “Hmmm, how did Pastor Philpot say I should answer questions like that…?”
All righty then. I’m satisfied. I don’t know diddly 'bout bamboo, but if you need some ‘splainin’ about meiosis in fruit flies, I’m your man.
Anyone who thinks mammalian vegetarians are necessarily peaceful has never seen an adult male moose in rut. Smaller vegetarians go through similar cycles, but a healthy adult male moose is a Buick on four legs with two antlers and no mercy.