'Splints' don't move the teeth. They keep them in place.
PLASTIC devices such as INVISALINE can move the teeth.
So IF your teeth actually have to be moved to prepare for surgery, you need to ask the ortho if the plastic device he called a 'splint' will move the teeth. You relayed here, that the ortho told you it would.
I have NO IDEA whether or not your teeth need to be moved in preparation for your surgery or need to stay in place. ONLY your surgeon would know that.
Surgeons need to work CLOSELY with the ORTHO. So, make sure you go to an ortho that your surgeon suggested you go to.