Even a peaceful division of the US would be something they would seriously benefit from. The US permanently divided against itself, each side easy to manipulate into a military conflict against the other. We would have nukes pointed at each other within a decade. It would be like the splitting of India and Pakistan, along with all the accompanying human rights atrocities.
The key word there is “right to.” If someone is willing to have a plea deal or move quickly to trial, they can. But if you want, and have the resources to pay for a lawyer, you can delay the process out for a very long time. Just because you have a right to a speedy trial doesn’t mean you have to exercise that right.