It is funny as my GPs just aren't frightened by rabbits at all either. My GP loves chasing Violet when they have to share the run - she is more scared by him! Athena hates GPs and tries to attack them through the cage bars, Zeus isn't bothered as he has know them since they were babies(they grew up together running round the kitchen). Don't know about Cosmos with them yet.
I figure as long as there is plenty of space there is little chance of the GPs being injured!
That piccy is so cute!
Caz