You all should be jealous because I got to meet little Aesop today and he's a stud! And so sweet!
As for the lucky bamboo (Dracaena sanderiana), I don't think it is a plant that has been studied sufficiently in reptiles enough to say one way or the other about toxicity with certainty. I always go to tortoise information sources looking for plant toxicity because of course they are going to be much more up to date on plant toxicity with strictly herbivore reptiles. The consensus is that it
may be toxic. This is the only source that actually has a 'why' behind it.
So...potentially toxic. That being said, as we're dealing with a panther chameleon and not a veiled I'm not too concerned by it since panthers so rarely chose to explore their herbivorous side. If he starts munching on other plants I'd take it away just in case, but if he doesn't munch on plants at all I wouldn't worry. Even if he takes a few bites of it one day it shouldn't be enough to cause serious problems unless he eats a whole stalk.