I don’t see why they can’t include him on a walk with the dogs every now and then. It allows him to see more of nature and visually explore a new environment. It would be local to where they live. They will already be social distancing. They will be going somewhere quiet and discreet anyway because they will want to be avoiding attention and detection.
I’ve just checked the LA lockdown rules and it states “Californians are still allowed - and encouraged - to get outside for fresh air and exercise. Park and beach closures vary at the local level, but the state is updating a running list of permitted outdoor activities, which can be found here. A few examples of permitted BMX biking, canoeing, cycling, rock climbing, crabbing, trampolining and walking the dog.”
I’m not saying they should be visiting beaches and mingling with people at parks, but they should be attempting to take him out on small, local walks. Honestly if this was a friend I would be staging an intervention.