I went trough similar things. Still do, to a certain extent.
It's a shame you can't keep home-schooling him because clearly, it's what he needs. But hey, that's life.
I had both my boys in mainstream far longer than I should have. Something I noticed, especially with difficult child 3, is that towards the end of each school year he got tired of it all, mentally exhausted and just not coping. I tried to get services in place to help and they just weren't available for us, either. And each year the problems would start earlier.
Both boys were depressed at school (which your son sounds like, too). They were bullied, especially difficult child 3. This made the anxiety problem much worse and this led to extreme school avoidance which, because our education authorities believe that any kid on the autism spectrum should be mixing it with other kids regardless, just made the problems worse and worse.
Can you talk to him about what he wants? Are there educational alternatives other than school? When is he old enough to get a job? It would be preferable for it to be a job that doesn't require him to interact with too many people - not working at McDonalds, for example.
We didn't know at the time but we could have got the boys into our TAFE college system as an alternative to later high school. They would have slipped in with the adult students and the support services are much better there. Someone who dropped out of high school can go to one of these colleges and complete their education, but while being treated as an adult and not demeaned the way some teachers treat students. Aspie kids are especially sensitive to even seeing someone else getting patronised or bullied. Our TAFEs can also give higher education qualifications which can springboard into university, if that's what the students want to do.
What about an apprenticeship? How much longer do you have to wait? Maybe this could be a path he could follow instead of school.
I don't get why the police took him to school in handcuffs - surely that is demeaning and bullying, just in a different form? Our cops only use handcuffs if they're charging someone AND that person is likely to be a danger. Merely to take a kid to school - I don't get it. If I were him, I wouldn't want to get out of bed either, I'd be so depressed. Not with you, but with LIFE.
This really does sound to me like depression and lack of purpose. If you live in New Orleans then it's likely he's still dealing with PTSD. It can go on for years. Throw in survivor guilt and I think you get what you're seeing now. People say that kids on the autism spectrum don't have feelings. They do! They often have stronger feelings, they just don't always express them in ways we recognise.
As for the water to get him up in the mornings - don't waste water by throwing it on him. I have a more effective way: get a water mist spray bottle. Set the nozzle on "jet" (test it in the sink). Then you squirt it up his leg, preferably inside the pajama leg. You use a lot less water that way, to a much greater effect (less need to change the bedding afterwards). If you can't get to the pajama leg, just try and get it on his skin somewhere under the bedclothes. It will feel cold & clammy and he will have a lot of trouble getting back to uninterrupted sleep. But warn him first - make sure you give him notice that you're coming in with the water bottle if he isn't out of bed when you get back from fetching it. Chances are he will soon learn to get himself up and dressed, just to foil you. Because that is what would happen with difficult child 1. (difficult child 1 sleeps with tracksuit pants on, which are great for squirting with water - you ease the elastic away from the ankle just enough to fit the nozzle there, and let fly. If you get it right the jet of water hits a home run).
Hang in there. I really don't know what you can do, he really needs you home to teach him but this clearly isn't an option for you. Life really isn't fair sometimes. But it's not your fault, so put guilt aside so you can think more clearly.