I always hesitate to ascribe motives to non-human animals, but the butterfly shouldn’t particularly “care” whether the pollen gets from its body back to a plant. If the butterfly is eating the pollen, then maybe there’s an advantage to hoovering up more just by getting close, but that doesn’t mean it wants to give any pollen back to other plants.
On the other hand, if the butterfly is eating the nectar and the pollination is an ancillary effect, then you have to start invoking more complicated mechanisms. Maybe successful pollination of the plants increases the food supply later? Maybe the flowers are not neutrally charged, but instead become oppositely charged when the pollen is ready to bias pollinators to come close at appropriate times? You can always construct some just-so story that fits the observed evidence, but where it becomes science is when you make predictions and test them.
On the other hand, if the butterfly is eating the nectar and the pollination is an ancillary effect, then you have to start invoking more complicated mechanisms. Maybe successful pollination of the plants increases the food supply later? Maybe the flowers are not neutrally charged, but instead become oppositely charged when the pollen is ready to bias pollinators to come close at appropriate times? You can always construct some just-so story that fits the observed evidence, but where it becomes science is when you make predictions and test them.