Sounds about right to me. Getting the ride working doesn't take that long, it's training, ADIPS testing and getting HSE clearance that takes time.
And I don't think HSE care, its only ADIPS that test amusement rides.
When creating a ride there's more to the overall attraction than just the coaster hardware. Queue lines, fire escape routes, electrical safety, access plans, crowd-size research, evacuation paths and procedures etc. There is a lot to sign off in satisfying various safety bodies.
Somone told me earlier that Icon had been testing with people on. Surely it's way too early for that?