Yes you can get them spayed at any age, it'sjust prefered at 6 months because they tend to be at peak physicalhealth. Espeically done at 6 months if they're going to be housed withother rabbits.
I have a dutch that had a stuck kit in the birthcanal and needed to have a c-section. The vet said that herreproductive system was falling apart in her hands and that if I didn'tget her spayed she would die. She was 3 years old at the timeand is fine to this day.
Two of my bunnies were spayed at age 4yrs. Both did fine and lived to be 12 and 13 yrs.Your vet should discuss the general risks of surgery with you beforethe surgery.