I don’t have access to a development kit. This question should be rather easy to answer for an FAE at NVIDIA. We are developing a product around this module.
The question is not if the casing is conductive (it is made of alu, it is), it is if the casing is connected via the copper trace on the outer edge of the JAX/i module.
It seems to have ground vias all around the PCB, which makes me think that the outer casing is also connected to the digital ground of the JAX/i PCB.
Also, this information should be stated in the datasheet of the module.