I feel that school is a valuable learning tool. But it's more than about knowing how to spell words correctly, knowing about punctuation, knowing geography and history and math. School helps kids of all ages learn how to listen, how to memorize, how to write creatively, how to study, how to be organized, how to access information, how to work as a team with other students. Students learn how to respect a teacher or principal (and ultimately, a boss or supervisor) and how to develop leadership qualities within themselves so that they can one day be the boss, the owner, the lead technician, the supervisor, or the team member who contributes positively to the team.
Even if your son goes to a trade school and studies to be a carpenter, a welder, an electrician, an X ray technician, an IT specialist, a plumber, a mechanic, whatever, he will need to know how to read well, how to learn facts, how to study, how to take in information and use it well, how to respect and respond to his instructor or mentor, and how to progress in his chosen field.
Trade schools are increasingly demanding due to new technology, and expanding fields.
So for now, while your son is young, I would encourage all three of you to get together on what is important. It almost sounds as if your husband is dismissing the value of schooling and academics, and is just saying "he can get a license some day and he doesn't need all this history of Egypt and the life of plants". Yes, perhaps your son will never ever need to know about chlorophyll and how plants grow, but if he listens, and studies, and participates in the science projects, he will learn life-long lessons about enriching his vocabulary, how to study, how to organize, how to prepare for a test or exam, and how to get along with the other kids who are watching beans grow.
Regardless of whether your son attends public school, or private school, or a virtual school, he is going to need to develop the qualities that will ultimately make him a good electrician, engineer, landscaper, construction worker, assembly worker, surgeon, teacher, researcher, or any other career you can name. The successful people in any field have some overlapping qualities, and now is the time for your son to develop those qualities. To allow him to be disinterested in school will be a real problem later on.
My son graduated from a very technical school and is a successful audio engineer. His school did not have courses like Freshman composition, or World History, or Psychology 101. Instead, he was immersed in a very demanding curriculum that was all about audio engineering, with lots of lab work. He loved it. But even in such a tech school, he still had to take a few courses that weren't all about the sound board and the controls and the science of audio engineering. In order to be a well-rounded engineer for live shows and events he had to take some courses in things like music copyright law, which he knew he would probably never encounter again, but he understood that it made him employable and more informed about his chosen field.