That's kind of harsh. You can't fault the cat for doing cat things when presented with an opportunity. If you have a multi-animal household you figure out how to keep everyone safe or re-home someone. It's not the cats fault it's a cat and they left a smaller very active lizard where it can see, hear and smell it.
This is coming from someone with 3 cats (one of them a kitten) and (a previous) bearded dragon owner. My dragon was donated to a city program in DC (where 3rd and 4th grade kids learn about reptiles and build them naturalistic environments to live in, it was really nice) because i felt that was a better fit than having him with me.