Yeah... But since the device is not doing anything meaningful, there's no way to tell if it actually is computing anything, rather than being a very expensive and very complicated random number generator. Because you don't need a quantum computer to generate a stream of meaningless numbers, a machine being capable of generating a stream of meaningless numbers doesn't demonstrate whether it's computing quantumly.
That's a good question. They run the system on a small scale and validate there. The assumption is that no new error mechanism magically switches on when the simulation gets large enough, but it is did there would be no way to know.
Hopefully large-scale, verifiable demonstrations become viable in the near future. But current they're just too hard to implement.
