Well, chams are not rocket scientists. I had a jax who shot at a cat's ear once. I can't think they consider that shooting their tongue is a weapon against a threat...it is too easily damaged. Maybe its a confusion of what behaviorists call "fixed action patterns". These are actions that the animal does without thinking about it first, but are not as complex as what we think of as "instinct". An example:
A mother duck is put in a box where she can hear but not see anything outside it. An unrelated duckling is put near the box and it starts calling for mom. The duck in the box reacts to the trigger and tries to get to the worried duckling. The box is removed, so she can see the duckling who was calling. But, she realizes it's not her own, and chases it away instead. The conflict is that there are two fixed action patterns working against each other. One is to defend a scared duckling. The other is to chase anything that is not her brood.