Hawaii has many instances of private companies contracting to run buses. Roberts, as a company, is large and professional. Individual bus routes can vary in behavior by the makeup of the students who ride the bus, and by the oversight of the individual bus driver. Is it a private school that you are thinking of enrolling your child? If so, does the private school maintain oversight of students' conduct while on the bus?
I speak from experience, so my intent is not just to being cranky, but I'd not set my 6 year old up for a pre-6am bus ride, with over an hour on the bus, and then a day of schooling. What sort of life is that for a very young child? If someone needs to "make an adjustment" so things work out, it should be the adults, not a 6 year old, IMHO.
Good luck with you planning and success with your choices.