Based on this information alone I think they have good reason to be concerned.
As a parent, I would be every bit as inquisitive about the situation as they are.
It is you who were in the physical fight and put him in jail.
They had to "bail him out".
If he had gone back to after that I would be inquiring daily as well.
Not only that, this statement speaks volumes, "took over his life like the sociopaths that they are".
Its this simple, YOU have no right to label them that way. If I bail my son out of jail because of a physical
altercation with you, you're damn right some life taking over would be going on.
And you have provided zero evidence that they are sociopaths. In fact you sound a lot more that way than his parents do.
The concept that after going back to you that they are to leave him alone until the next jail incident
If they really had "taken over his life" I'm pretty sure he would still be in their house.
I would be worried for his safety and well being as well.
You on the other hand have a couple years invested, while they have decades.
Your attitude is way wrong.