This is very common. All schools have "general" special education teachers who serve students who spend most of their time in gen ed (called resource teachers, cross-category, mild/mod depending on the district) or do not have more specialized or intensive needs. Then, there are programs focused on specific needs that are located in different schools. You are right that schools are obligated to write IEPs based on the students needs and not the school's resources. This is what your team has done. And based on the child-focused, need-driven IEP that was not limited by your home school's resources, your child's IEP will be implemented at a different school that has the programming/resources to implement it.