I'm afraid you're looking at this the wrong way. This woman works. Perhaps she's a single mother; perhaps she simply chooses to work.
She doesn't WANT to homeschool the child; she wants all the rest of us, the residents of the "village," to take care of her child.
So she leaves him in the school, which is required BY LAW (mostly by judicial fiat, as it happens) to put him in the "least restrictive environment--and d*mn the teachers or the other students.
Instead of the standard, pat, one-size-fits-all simplistic answers, you need to understand the real situation here.
If you homeschool your children, you do not get the extra services that a special ed children need. You do not get speech therapy, occupational therapy, physical therapy, etc.
Most parents are not trained in those fields, and I don't know of many that can pay for those services. Insurance will not cover those services.
Most parents with special ed students not only send their kids to school, but they also pay for some supplemental private therapies.
This mom may work in order to pay for those supplemental servcies. They usually run about $100/hour for the services.