Yes, rabbits should be quarantined, and they are VERY territorial. We spent $600 patching up an abandoned rabbit that needed multiple drains after their owner didn't follow introduction instructions.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry